I do have a table with more than 100000 data elements, but there are almost 350 blank rows within. How do I delete this blank rows using phpmyadmin? Manually deleting is a tedious task.
The general answer is:
DELETE FROM table_name WHERE some_column = '';
or
DELETE FROM table_name WHERE some_column IS NULL;
See: http://dev.mysql.com/doc/refman/5.0/en/delete.html
More info when you post your tables!~
Also, be sure to do:
SELECT * FROM table_name WHERE some_column = '';
before you delete, so you can see which rows you are deleting! I think in phpMyAdmin you can even just do the select and then "select all" and delete, but I'm not sure. This would be pretty fast, and very safe.
I am doing the mysql operation in command prompt in windows. And the basic queries:
delete * from table_name where column=''
and
delete * from table_name where column='NULL'
doesn't work. I don't know whether it works in phpmyadmin sqlcommand builder. Anyway:
delete * from table_name where column is NULL
works fine.
I have a PHP script that automatically removes empty rows based on column data types.
That allows me to define "emptiness" differently for different column types.
e.g.
table
first_name (varchar) | last_name (varchar) | some_qty ( int ) | other_qty (decimal)
DELETE FROM `table` WHERE
(`first_name` IS NULL OR `first_name` = '')
AND
(`last_name` IS NULL OR `last_name` = '')
AND
(`some_qty` IS NULL OR `some_qty` = 0)
AND
(`other_qty` IS NULL OR `other_qty` = 0)
Since "0" values are meaningless in my system, I count them as empty. But I found out that if you do (first_name = 0) then you will always get true, because strings always == 0 in MySQL. So I tailor the definition of "empty" to the data type.
This procedure will delete any row for all columns that are null ignoring the primary column that may be set as an ID. I hope it helps you.
DELIMITER //
CREATE PROCEDURE DeleteRowsAllColNull(IN tbl VARCHAR(64))
BEGIN
SET #tbl = tbl;
SET SESSION group_concat_max_len = 1000000;
SELECT CONCAT('DELETE FROM `',#tbl,'` WHERE ',(REPLACE(group_concat(concat('`',COLUMN_NAME, '` is NULL')),',',' AND ')),';') FROM INFORMATION_SCHEMA.COLUMNS WHERE table_name = #tbl AND COLUMN_KEY NOT LIKE 'PRI' into #delete_all;
PREPARE delete_all FROM #delete_all;
EXECUTE delete_all;
DEALLOCATE PREPARE delete_all;
END //
DELIMITER ;
Execute the procedure like this.
CALL DeleteRowsAllColNull('your table');
I know this has already been answered and has got a tick, but I wrote a small function for doing this, and thought it might be useful to other people.
I call my function with an array so that I can use the same function for different tables.
$tableArray=array("Address", "Email", "Phone"); //This is the column names
$this->deleteBlankLines("tableName",$tableArray);
and here is the function which takes the array and builds the delete string
private function deleteBlankLines($tablename,$columnArray){
$Where="";
foreach($columnArray as $line):
$Where.="(`".$line."`=''||`".$line."` IS NULL) && ";
endforeach;
$Where = rtrim($Where, '&& ');
$query="DELETE FROM `{$tablename}` WHERE ".$Where;
$stmt = $this->db->prepare($query);
$stmt->execute();
}
You can use this function for multiple tables. You just need to send in a different table name and array and it will work.
My function will check for a whole row of empty columns or NULL columns at the same time. If you don't need it to check for NULL then you can remove that part.
Related
I'm trying to update a column (in this case, a date) that is present on most of the tables on my database. Sadly, my database has more than 100 tables already created and full of information. Is there any way to loop through them and just use:
UPDATE SET date = '2016-04-20' WHERE name = 'Example'
on the loop?
One painless option would be to create a query which generates the UPDATE statements you want to run on all the tables:
SELECT CONCAT('UPDATE ', a.table_name, ' SET date = "2016-04-20" WHERE name = "Example";')
FROM information_schema.tables a
WHERE a.table_schema = 'YourDBNameHere'
You can copy the output from this query, paste it in the query editor, and run it.
Update:
As #PaulSpiegel pointed out, the above solution might be inconvenient if one be using an editor such as HeidiSQL, because it would require manually copying each record in the result set. Employing a trick using GROUP_CONCAT() would give a single string containing every desired UPDATE query in it:
SELECT GROUP_CONCAT(t.query SEPARATOR '; ')
FROM
(
SELECT CONCAT('UPDATE ', a.table_name,
' SET date = "2016-04-20" WHERE name = "Example";') AS query,
'1' AS id
FROM information_schema.tables a
WHERE a.table_schema = 'YourDBNameHere'
) t
GROUP BY t.id
You can use SHOW TABLES command to list all tables in database. Next you can check if column presented in table with SHOW COLUMNS command. It can be used this way:
SHOW COLUMNS FROM `table_name` LIKE `column_name`
If this query returns result, then column exists and you can perform UPDATE query on it.
Update
You can check this procedure on sqlfiddle.
CREATE PROCEDURE UpdateTables (IN WhereColumn VARCHAR(10),
IN WhereValue VARCHAR(10),
IN UpdateColumn VARCHAR(10),
IN UpdateValue VARCHAR(10))
BEGIN
DECLARE Finished BOOL DEFAULT FALSE;
DECLARE TableName VARCHAR(10);
DECLARE TablesCursor CURSOR FOR
SELECT c1.TABLE_NAME
FROM INFORMATION_SCHEMA.COLUMNS c1
JOIN INFORMATION_SCHEMA.COLUMNS c2 ON (c1.TABLE_SCHEMA = c2.TABLE_SCHEMA AND c1.TABLE_NAME = c2.TABLE_NAME)
WHERE c1.TABLE_SCHEMA = DATABASE()
AND c1.COLUMN_NAME = WhereColumn
AND c2.COLUMN_NAME = UpdateColumn;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET Finished = TRUE;
OPEN TablesCursor;
MainLoop: LOOP
FETCH TablesCursor INTO TableName;
IF Finished THEN
LEAVE MainLoop;
END IF;
SET #queryText = CONCAT('UPDATE ', TableName, ' SET ', UpdateColumn, '=', QUOTE(UpdateValue), ' WHERE ', WhereColumn, '=', QUOTE(WhereValue));
PREPARE updateQuery FROM #queryText;
EXECUTE updateQuery;
DEALLOCATE PREPARE updateQuery;
END LOOP;
CLOSE TablesCursor;
END
This is just an example how to iterate through all tables in database and perform some action with them. Procedure can be changed according to your needs.
Assuming you are using MySQL, You can use Stored Procedure.
This post is a very helpful.
Mysql-loop-through-tables
I need to update the sort order column based on the sequence of primary key values I get as array list from ajax call. For example I have 2 coulmns (ID, Sortorder) with values (23,1)(32,2)(21,3)(43,4), now the user from the frontend moves the 3rd row(21,3) above second row(32,2) and I get the ID array sequence as 23, 21, 32, 43 which I have to maintain. From this list, I am trying to update the sororder as per the sequence, so the database table values should look as (23,1)(32,3)(21,2)(43,4). Could you help me to get this DB update statement.
Attached the print screen for better understanding:
Java logic I have, trying to find an update sql statement to loop from an array list. I have ~1000 rows in my table and with my logic, this would trigger 1000 update queries, I don't think this is efficient. Trying to find an alternate efficient way.
Connection conn = null;
PreparedStatement pstmt = null;
conn = getConnection();
String query = "update Sortordertable set sortorder = ? where Id = ? ";
pstmt = conn.prepareStatement(query); // create a statement
String str[]=String.valueOf(s.getRecordId()).split(";");//id1;id;id3;.... list I get from ajax call
for(int i=0;i<str.length();i++)
{
pstmt.setId(1,i++); //set sortorder value as 1, 2, 3..
pstmt.setInt(2, str[i]); // In this line I want to use my array-list to update my table.
pstmt.executeUpdate(); // execute update statement
}
For the specific use case you have showed, you could use the following query, which would update only the rows with id=32 or id=23.
UPDATE t1 SET
sortorder = CASE WHEN id = 32 THEN 3 ELSE 2 END
WHERE id IN (32, 21);
This could be adapted for multiple updates if you don't update the database after each operation. but will grow with the number of operations made by the user before the update is triggered.
Edit to address comment:
If, as in the example given in your comment, you want to move the row with order 4 to the first row, you can use the following:
UPDATE t1 SET
sortorder = CASE WHEN sortorder = 4 THEN 1 ELSE sortorder + 1 END
WHERE sortorder <= 4;
I've added a where clause in that last query to illustrate that you can easily adapt this to different use case.
Here's what you can do:
DELIMITER $$
CREATE PROCEDURE `sp_update_positions`(
IN `p_positions` VARCHAR(255)
)
BEGIN
SET #positions = REPLACE(p_positions, ',', '),(');
SET #positions = CONCAT('(', #positions, ')');
DROP TEMPORARY TABLE IF EXISTS tmpPositions;
CREATE TEMPORARY TABLE tmpPositions(
`position` int(10) unsigned NOT NULL AUTO_INCREMENT PRIMARY KEY,
`order_id` int(10) unsigned NOT NULL
);
SET #insertString = CONCAT('INSERT INTO tmpPositions (`order_id`) VALUES ', #positions);
PREPARE insertStatement FROM #insertString;
EXECUTE insertStatement;
DEALLOCATE PREPARE insertStatement;
UPDATE orders
INNER JOIN tmpPositions ON order_id = orders.id
SET orders.Sortorder = tmpPositions.position;
SELECT ROW_COUNT() AS rowCount;
END$$
DELIMITER ;
Then you call it like this:
CALL sp_update_positions('24,23,21,22');
I want to select a bunch of rows from a mysql database and update the viewed attribute of those once selected (this is a kind of 'I have read these' flag).
Initially I did something like this:
update (
select a, b, c
from mytable
where viewed = '0'
)
set viewed = '1';
This selects the rows nicely and updates their viewed attribute as required. But it does not return the selected rows from the subquery.
Is there a clause I can add, or perhaps I need to store the subquery, etc...? I did consider a transaction but I ended up with the same problem. I have not tried a stored procedure...
Please can someone advise / point me in the right direction on how to do what I do above but in addition return the selected tables from the subquery?
Thanks in advance.
Update:
As pointed out by #Barmar, #a_horse_with_no_name, #fancyPants and #George Garchagudashvil...
In MySQL you have to use two statements to select and update, and not a nested statement as in my initial post, if you want to return the selected rows.
e.g.
begin;
select a, b, c
from mytable
where viewed = '0';
update mytable
set viewed = '1'
where viewed = '0';
commit;
thanks guys.
I would create a simple function:
DELIMITER $$
DROP FUNCTION IF EXISTS `mydb`.`updateMytable`$$
CREATE
/*[DEFINER = { user | CURRENT_USER }]*/
FUNCTION `mydb`.`updateMytable`() RETURNS TEXT
BEGIN
SET #updated := '';
UPDATE mytable
SET viewed = 1
WHERE viewed = 0
AND (
SELECT #updated := CONCAT_WS(',', #updated, id)
) != ''
;
RETURN TRIM(LEADING ',' FROM #updated);
END$$
DELIMITER ;
which updates tables and returns concatenated ids.
From php you call this:
SELECT mydb.updateMytable()
and you get ids in a stirng: 1,2,7,54,132 etc...
Update:
my function is returning string containing comma separated ids:
'1,5,7,52,...' these ids are only which would have been updated during the function call,
better php-mysql example would be (you may and would use PDO):
$query = "SELECT mydb.updateMytable()";
$res = mysql_query($query);
$arr = mysql_fetch_array($res);
$ids = explode(',', $arr[0]);
// now you can do whatever you want to do with ids
foreach ($ids as $id)
{
echo "Hoorah: updated $id\n";
}
also remember to change mydb and mytable according to your database names
Final
because you need more complex functionality, simply run two query:
First run:
SELECT a, b, c
FROM mytable
WHERE viewed = 0
Next run:
UPDATE mytable
SET viewed = 1
WHERE viewed = 0
I have plenty of tables in MySQL which which contains zero date in dateTime column 0000-00-00 00:00:00
Using some sort of admin settings, Is it possible to disable zero dates and replace all zero with static value say 1-1-1900?
EDIT:
I am working on database migration which involves migrating more than 100 MySQL tables to SQL Server.
Can I avoid executing scripts on each table manually by setting up
database mode?
To change existings values you could use a query like this:
UPDATE tablename SET date_column = '1900-01-01' WHERE date_column = '0000-00-00';
If you want to automate the UPDATE query you can use a prepared statement:
SET #sql_update=CONCAT_WS(' ', 'UPDATE', CONCAT(_schema, '.', _table),
'SET', _column, '=', '\'1900-01-01\'',
'WHERE', _column, '=', '\'0000-00-00\'');
PREPARE stmt FROM #sql_update;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
And you can loop through all colums in all tables on the current schema that are declared as date:
SELECT
table_schema,
table_name,
column_name
FROM
information_schema.columns
WHERE
table_schema=DATABASE() AND data_type LIKE 'date%'
To loop through all columns you could use a stored procedure:
DELIMITER //
CREATE PROCEDURE update_all_tables() BEGIN
DECLARE done BOOLEAN DEFAULT FALSE;
DECLARE _schema VARCHAR(255);
DECLARE _table VARCHAR(255);
DECLARE _column VARCHAR(255);
DECLARE cur CURSOR FOR SELECT
CONCAT('`', REPLACE(table_schema, '`', '``'), '`'),
CONCAT('`', REPLACE(table_name, '`', '``'), '`'),
CONCAT('`', REPLACE(column_name, '`', '``'), '`')
FROM
information_schema.columns
WHERE
table_schema=DATABASE() AND data_type LIKE 'date%';
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done := TRUE;
OPEN cur;
columnsLoop: LOOP
FETCH cur INTO _schema, _table, _column;
IF done THEN
LEAVE columnsLoop;
END IF;
SET #sql_update=CONCAT_WS(' ', 'UPDATE', CONCAT(_schema, '.', _table),
'SET', _column, '=', '\'1900-01-01\'',
'WHERE', _column, '=', '\'0000-00-00\'');
PREPARE stmt FROM #sql_update;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END LOOP columnsLoop;
CLOSE cur;
END//
DELIMITER ;
Please see an example here.
This is an old question but was running into a similar problem except I was trying to set the 0000-00-00 to NULL.
Was trying to query this
UPDATE tablename SET date_column = NULL WHERE date_column = '0000-00-00';
and was getting the following error :
Incorrect date value: '0000-00-00' for column 'date_column' at row 1
Turns out the following query without '' around the 0000-00-00 worked !
UPDATE tablename SET date_column = NULL WHERE date_column = 0000-00-00;
You can change existing values running that query
update your_table
set date_column = '1900-01-01'
where date_column = '0000-00-00'
And you can change the definition of your table to a specfic default value or null like this
ALTER TABLE your_table
CHANGE date_column date_column date NOT NULL DEFAULT '1900-01-01'
You have two options.
Option One - In the programming language of your choice (you can even do this with Stored Procedures):
Loop through your INFORMATION_SCHEMA, probably COLUMNS and build a query to get back the tables you need to affect, i.e.
-
SELECT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME='date' AND TABLE_SCHEMA='<YOUR DB NAME>'
or maybe even better
SELECT TABLE_NAME,COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS
WHERE COLUMN_NAME in ('timestamp','date','datetime')
AND TABLE_SCHEMA='<YOUR DB NAME>'
Store results and then loop through them. Each loop, create a new query. In MySQL that would be a Stored Procedure with Prepared Statements, AKA:
-
#string = CONCAT("UPDATE ", #table_name, " SET ", #column_name, "='1-1-1900' WHERE ", #column_name, "=0000-00-00 00:00:00");
PREPARE stmt FROM #string;
EXECUTE stmt;
That wouldn't be too tough to write up.
Option Two - Another example, while certainly more low tech, may be no less effective. After doing a mysqldump and before doing your export, you can do a simple search-replace in the file. Vim or any other text editor would do this quite expertly and would allow you to replace 0000-00-00 00:00:00 with 1-1-1900. Because you are almost definitely not going to find situations where you DON'T want that to be replaced, this could be the easiest option for you. Just throwing it out there!
In my opinion, you could generate all updates the simplest way:
select
concat('UPDATE ',TABLE_NAME,' SET ',COLUMN_NAME,'=NULL WHERE ',COLUMN_NAME,'=0;')
from information_schema.COLUMNS
where TABLE_SCHEMA = 'DATABASE_NAME' and DATA_TYPE in ('datetime', 'date', 'time');
Just replace DATABASE_NAME to your DB name, and execute all updates.
Alter your Table as
ALTER TABLE `test_table`
CHANGE COLUMN `created_dt` `created_dt` date NOT NULL DEFAULT '1900-01-01';
but before Altering table you need to update the existing value as juergen d said
update test_table
set created_dt= '1900-01-01'
where created_dt= '0000-00-00'
You can update your table by filtering where dates are equals to 0 and you can define a default value to the column.
Prefix: You might want to check the concept of ETL in DataWareHousing, there are tools which should do the simple conversions for you, even Open Source ones like Kettle/Pentaho.
But this one is easy when you use any programming language capable of composing SQL queries. I have made an example in perl, but php or java would do also the job:
#!/usr/bin/perl
use strict;
use warnings;
use DBI;
my $user='geheim';
my $pass='secret';
my $dbh = DBI->connect( "dbi:mysql:host=localhost:database=to_convert:port=3306", $user, $pass ) or die $DBI::errstr;
# Prints out all the statements needed, might be checked before executed
my #tables = #{ $dbh->selectall_arrayref("show tables") };
foreach my $tableh ( #tables){
my $tabname = $tableh->[0];
my $sth=$dbh->prepare("explain $tabname");
$sth->execute();
while (my $colinfo = $sth->fetchrow_hashref){
if ($colinfo->{'Type'} =~ /date/i && $colinfo->{'Null'} =~ /yes/i){
print ("update \`$tabname\` set \`" . $colinfo->{'Field'} . "\` = '1990-01-01' where \`" . $colinfo->{'Field'} . "\` IS NULL; \n");
print ("alter table \`$tabname\` change column \`" . $colinfo->{'Field'} . "\` \`" . $colinfo->{'Field'} . "\` " . $colinfo->{'Type'} . " not null default '1990-01-01'; \n");
}
}
}
This does not change anything, but when the database has tables like:
localmysql [localhost]> explain dt;
+-------+------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+------+------+-----+---------+-------+
| a | date | YES | | NULL | |
+-------+------+------+-----+---------+-------+
1 row in set (0.00 sec)
localmysql [localhost]> explain tst
-> ;
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| atime | datetime | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)
it produces the Statements:
update `dt` set `a` = '1990-01-01' where `a` IS NULL;
alter table `dt` change column `a` `a` date not null default '1990-01-01';
update `tst` set `atime` = '1990-01-01' where `atime` IS NULL;
alter table `tst` change column `atime` `atime` datetime not null default '1990-01-01';
This list can then be reviewed and executed as Statements.
Hope that Helps!
As this is for migration, I would suggest that you simply wrap your tables in views which does the conversion as you export the data. I have used the below concept moving data from MySQL to postgress which has the same problem.
Each table should be proxied by something like this;
CREATE VIEW migration_mytable AS
SELECT field1, field2,
CASE field3
WHEN '0000-00-00 00:00:00'
THEN '1900-01-01 00:00:00'
ELSE field3
END CASE AS field3
FROM mytable;
You should be able to write a script which generate this for you from the catalog, in case you have a great deal of tables to take care of.
You should then be able to import the data into your SqlServer table (using a bridge like this), and simply running a query like;
INSERT INTO sqlserver.mytable SELECT * FROM mysql.migration_mytable;
How do I check if an index exists on a table field in MySQL?
I've needed to Google this multiple times, so I'm sharing my Q/A.
Use SHOW INDEX like so:
SHOW INDEX FROM [tablename]
Docs: https://dev.mysql.com/doc/refman/5.0/en/show-index.html
Try:
SELECT * FROM information_schema.statistics
WHERE table_schema = [DATABASE NAME]
AND table_name = [TABLE NAME] AND column_name = [COLUMN NAME]
It will tell you if there is an index of any kind on a certain column without the need to know the name given to the index. It will also work in a stored procedure (as opposed to show index)
show index from table_name where Column_name='column_name';
SHOW KEYS FROM tablename WHERE Key_name='unique key name'
will show if a unique key exists in the table.
Use the following statement:
SHOW INDEX FROM *your_table*
And then check the result for the fields: row["Table"], row["Key_name"]
Make sure you write "Key_name" correctly
To look at a table's layout from the CLI, you would use
desc mytable
or
show table mytable
Adding to what GK10 suggested:
Use the following statement: SHOW INDEX FROM your_table
And then check the result for the fields: row["Table"],
row["Key_name"]
Make sure you write "Key_name" correctly
One can take that and work it into PHP (or other language) wrapped around an sql statement to find the index columns. Basically you can pull in the result of SHOW INDEX FROM 'mytable' into PHP and then use the column 'Column_name' to get the index column.
Make your database connection string and do something like this:
$mysqli = mysqli_connect("localhost", "my_user", "my_password", "world");
$sql = "SHOW INDEX FROM 'mydatabase.mytable' WHERE Key_name = 'PRIMARY';" ;
$result = mysqli_query($mysqli, $sql);
while ($row = $result->fetch_assoc()) {
echo $rowVerbatimsSet["Column_name"];
}
Try to use this:
SELECT TRUE
FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE
WHERE TABLE_SCHEMA = "{DB_NAME}"
AND TABLE_NAME = "{DB_TABLE}"
AND COLUMN_NAME = "{DB_INDEXED_FIELD}";
You can use the following SQL to check whether the given column on table was indexed or not:
select a.table_schema, a.table_name, a.column_name, index_name
from information_schema.columns a
join information_schema.tables b on a.table_schema = b.table_schema and
a.table_name = b.table_name and
b.table_type = 'BASE TABLE'
left join (
select concat(x.name, '/', y.name) full_path_schema, y.name index_name
FROM information_schema.INNODB_SYS_TABLES as x
JOIN information_schema.INNODB_SYS_INDEXES as y on x.TABLE_ID = y.TABLE_ID
WHERE x.name = 'your_schema'
and y.name = 'your_column') d on concat(a.table_schema, '/', a.table_name, '/', a.column_name) = d.full_path_schema
where a.table_schema = 'your_schema'
and a.column_name = 'your_column'
order by a.table_schema, a.table_name;
Since the joins are against INNODB_SYS_*, the match indexes only came from the INNODB tables only.
If you need to check if a index for a column exists as a database function, you can use/adopt this code.
If you want to check if an index exists at all regardless of the position in a multi-column-index, then just delete the part AND SEQ_IN_INDEX = 1.
DELIMITER $$
CREATE FUNCTION `fct_check_if_index_for_column_exists_at_first_place`(
`IN_SCHEMA` VARCHAR(255),
`IN_TABLE` VARCHAR(255),
`IN_COLUMN` VARCHAR(255)
)
RETURNS tinyint(4)
LANGUAGE SQL
DETERMINISTIC
CONTAINS SQL
SQL SECURITY DEFINER
COMMENT 'Check if index exists at first place in sequence for a given column in a given table in a given schema. Returns -1 if schema does not exist. Returns -2 if table does not exist. Returns -3 if column does not exist. If index exists in first place it returns 1, otherwise 0.'
BEGIN
-- Check if index exists at first place in sequence for a given column in a given table in a given schema.
-- Returns -1 if schema does not exist.
-- Returns -2 if table does not exist.
-- Returns -3 if column does not exist.
-- If the index exists in first place it returns 1, otherwise 0.
-- Example call: SELECT fct_check_if_index_for_column_exists_at_first_place('schema_name', 'table_name', 'index_name');
-- check if schema exists
SELECT
COUNT(*) INTO #COUNT_EXISTS
FROM
INFORMATION_SCHEMA.SCHEMATA
WHERE
SCHEMA_NAME = IN_SCHEMA
;
IF #COUNT_EXISTS = 0 THEN
RETURN -1;
END IF;
-- check if table exists
SELECT
COUNT(*) INTO #COUNT_EXISTS
FROM
INFORMATION_SCHEMA.TABLES
WHERE
TABLE_SCHEMA = IN_SCHEMA
AND TABLE_NAME = IN_TABLE
;
IF #COUNT_EXISTS = 0 THEN
RETURN -2;
END IF;
-- check if column exists
SELECT
COUNT(*) INTO #COUNT_EXISTS
FROM
INFORMATION_SCHEMA.COLUMNS
WHERE
TABLE_SCHEMA = IN_SCHEMA
AND TABLE_NAME = IN_TABLE
AND COLUMN_NAME = IN_COLUMN
;
IF #COUNT_EXISTS = 0 THEN
RETURN -3;
END IF;
-- check if index exists at first place in sequence
SELECT
COUNT(*) INTO #COUNT_EXISTS
FROM
information_schema.statistics
WHERE
TABLE_SCHEMA = IN_SCHEMA
AND TABLE_NAME = IN_TABLE AND COLUMN_NAME = IN_COLUMN
AND SEQ_IN_INDEX = 1;
IF #COUNT_EXISTS > 0 THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END$$
DELIMITER ;
You can't run a specific show index query because it will throw an error if an index does not exist. Therefore, you have to grab all indexes into an array and loop through them if you want to avoid any SQL errors.
Heres how I do it. I grab all of the indexes from the table (in this case, leads) and then, in a foreach loop, check if the column name (in this case, province) exists or not.
$this->name = 'province';
$stm = $this->db->prepare('show index from `leads`');
$stm->execute();
$res = $stm->fetchAll();
$index_exists = false;
foreach ($res as $r) {
if ($r['Column_name'] == $this->name) {
$index_exists = true;
}
}
This way you can really narrow down the index attributes. Do a print_r of $res in order to see what you can work with.