I want to get rows of a table such that no column value is null. No hardcoding of column values. I have hundreds of column names so.
Output should be only row 2 since all that row has the values for all the columns. I do not want to specify all the column names for is not null. It should take it programmatically. Even if i add a new column it should work without changing the query. That is my vision.
I found something, but that means using CURSOR
DECLARE #ColumnName VARCHAR(200)
DECLARE #ColumnCount INT
DECLARE #sql VARCHAR(400)
CREATE TABLE #tempTable (Id INT)
DECLARE GetNonNullRows CURSOR
FOR
SELECT c.NAME, (SELECT COUNT(*) FROM sys.columns col WHERE col.object_id = c.OBJECT_ID) FROM sys.tables AS t
JOIN sys.columns AS c ON t.object_id = c.object_id
WHERE t.name = 'SomeTable' AND t.type = 'U'
OPEN GetNonNullRows
FETCH NEXT FROM GetNonNullRows INTO #ColumnName, #ColumnCount
WHILE ##FETCH_STATUS = 0
BEGIN
SET #sql = 'SELECT st.UniqueId FROM SomeTable AS st WHERE ' + CONVERT(varchar, #ColumnName) + ' IS NOT NULL'
INSERT INTO #tempTable
EXEC (#sql)
FETCH NEXT FROM GetNonNullRows INTO #ColumnName, #ColumnCount
END
CLOSE GetNonNullRows
DEALLOCATE GetNonNullRows
SELECT * FROM SomeTable AS st1
WHERE st1.UniqueId IN (SELECT Id FROM #tempTable AS tt
GROUP BY Id
HAVING COUNT(Id) = #ColumnCount)
DROP TABLE #tempTable
Let me to explain this a little.
First i create cursor which iterate through all the columns of one table. For each column, I've create sql script to search in table for not null values for selected column. For those rows that satisfies criteria, I take its unique ID and put in temp table, and this job I am using for all columns.
At the end only ID's which count is like columns count are your result set, because only rows that have identical number of appearances like number of columns in table may be rows with all non null values in all columns.
Try this ::
SELECT * FROM mytable WHERE column IS NOT NULL
try this
SELECT *
FROM your_table_name
where coalesce(column_1, column_2, column_3, ...., column_n) is not null
SQL alone cannot express such a concept.
You have to dinamically build the SQL query according to the table definition using some procedural language.
In Oracle you can use the dictionay view USER_TAB_COLUMNS to build the column list.
try using IS NOT NULL
SELECT * FROM table WHERE field_name IS NOT NULL
For more information, check out the mysql manual on working with null values.
Related
I have a lot of different tables in my database, and I need somehow to get last inserted rows from those tables. Like social networks feeds. Also, those tables are have not random, but unknown names, because they all generated by users.
In example:
I have tables: A,B,C and D with 5k rows in each table.
I need somehow to get last rows from those tables and make it ordered by id, like we do in a simple query: "SELECT * FROM table A ORDER BY id DESC", but I'm looking for something like: "SELECT * FROM A,B,C,D ORDER BY id DESC".
Tables have same structure.
You can use union and order by if your tables have the same structure. Something like:
select *
from (
select * from A
union all
select * from B
union all
select * from C
) order by id desc
If the tables don't have the same structure then you cannot select * from all and order them and you might want to do two queries. First would be:
select id, tableName
from (
select id, 'tableA' as tableName from A
union all
select id, 'tableB' as tableName from B
union all
select id, 'tableC' as tableName from C
) order by id desc
Which will give you the last IDs and the tables where they are inserted. And then you need to get the rows from each respective table.
With pure Mysql it will be a bit hard. You can select the table names like:
SELECT table_name FROM information_schema.tables; but still how to use them in the statement? You will need to generate it dynamically
A procedure to generate the query dynamically can be something like ( I haven't tested it but I believe with some debugging it should work) :
DELIMITER $$
CREATE PROCEDURE buildQuery (OUT v_query VARCHAR)
BEGIN
DECLARE v_finished INTEGER DEFAULT 0;
DECLARE v_table_count INTEGER DEFAULT 0;
DECLARE v_table varchar(100) DEFAULT "";
-- declare cursor for tables (this is for all tables but can be changed)
DEClARE table_cursor CURSOR FOR
SELECT table_name FROM information_schema.tables;
-- declare NOT FOUND handler
DECLARE CONTINUE HANDLER
FOR NOT FOUND SET v_finished = 1;
OPEN table_cursor;
SET v_query="select * from ( ";
get_table: LOOP
FETCH table_cursor INTO v_table;
SET v_table_count = v_table_count + 1;
IF v_finished = 1 THEN
LEAVE get_table;
END IF;
if v_table_count>1 THEN
CONCAT(vquery, " UNION ALL ")
END IF;
SET v_query = CONCAT(vquery," select * from ", v_table );
END LOOP get_table;
SET v_query = CONCAT(vquery," ) order by id desc " );
-- here v_query should be the created query with UNION_ALL
CLOSE table_cursor;
SELECT #v_query;
END$$
DELIMITER ;
If each table's id is counted seperatly you can't order by ID, so you'll need to calculate a global id and use it on all of your tables.
You can do it as follows:
Assuming you have 2 tables A,B:
Create Table A(id int NOT NULL auto_increment, name varchar(max), value varchar(max), PRIMARY_KEY(id));
Create Table B(id int NOT NULL auto_increment, name varchar(max), value varchar(max), PRIMARY_KEY(id));
Add another table IDS with id as auto increment primary key.
Create table IDS (id int NOT NULL auto_increment, ts Timestamp default CURRENT_TIMESTAMP, PRIMARY_KEY(id));
For all your tables id column should use now the id from the IDS table as foreign key instead of auto increment.
Create Table A(id int NOT NULL auto_increment, name varchar(max), value varchar(max), PRIMARY_KEY(id),CONSTRAINT fk_A_id FOREIGN KEY(id) REFERENCE IDS(id) ON DELETE CASCADE ON UPDATE CASCADE);
Create Table B(id int NOT NULL auto_increment, name varchar(max), value varchar(max), PRIMARY_KEY(id),CONSTRAINT fk_A_id FOREIGN KEY(id) REFERENCE IDS(id) ON DELETE CASCADE ON UPDATE CASCADE);
for each table add before insert trigger, the trigger should first insert row to the IDS table and insert the LAST_INSERT_ID the table.
Create TRIGGER befor_insert_A BEFORE INSERT On A
FOR EACH ROW
BEGIN
insert into IDS() values ();
set new.id = LAST_INSERT_ID();
END
Create TRIGGER befor_insert_B BEFORE INSERT On B
FOR EACH ROW
BEGIN
insert into IDS() values ();
set new.id = LAST_INSERT_ID();
END
Now you can create view from all tables with union all, the rows of v can be sorted now by the id and give the cronlogic order of insertion.
Create view V AS select * from A UNION ALL select * from B
For example you can query on V the latest 10 ids:
select * from V Order by id desc LIMIT 10
Other option is to add timestamp for each table and sort the view by the timestamp.
Hi are you looking for this? However the id is not a good column to see the last updated among different tables.
select *
from A
join B
on 1=1
join C
on 1=1
join D
on 1=1
order by A.id desc
I need to copy/ insert all values with a certain where clause from table A to table B (basically from Main tables to respective history tables).
I don't want to specify the column names as I want to create a generic approach which will be able to use for all the tables that will need the ingestion.
Unfortunately, the attributes in table A are not always in the same order as it is in tableB, so I can't use select * into #temp from TableA and then insert into tableB from #temp. Plus TableB has generic 3 sys columns which we are generated for audit purposes.
My idea was to use the Info schema to get the column names. Then somehow use the result to get all the values from the asking table and add on top the generic sys columns. Is it possible to do?
I got the column names by using Info schema.
Select
COLUMN_NAME
FROM INFORMATION_SCHEMA.columns
where TABLE_NAME = 'TableA'
The SYS columns are:
sys_date=Getdate ()
,sys_flag='1'
,sys_name=SYSTEM_USER
Use Dynamic Query SQL Server
Please change table Name accordingly.
Declare #Table_Name varchar(50)
SET #Table_Name ='LoginMst'
Declare #Query varchar(8000)
Declare #ColumnNames varchar (8000)
set #ColumnNames = ''
select #ColumnNames =
case when #ColumnNames = ''
then column_name
else #ColumnNames + coalesce(',' + column_name, '')
end
from information_schema.columns where Table_Name=#Table_Name
SET #Query='insert into '+#Table_Name+'_Log ('+#ColumnNames+',sys_date,sys_flag,sys_name'+')
select '+#ColumnNames+',Getdate(),''1'',SYSTEM_USER from '+ 'LoginMst'
--print #Query
Exec(#Query)
You will require iterating all the tables you wish to take backup of. You will require adding the where clause too.
How do I insert a sql row into a new table where it meets criteria but resets the id value. In other words, copy the row, but reset the id value.
This is my current sql
INSERT INTO followers_lost SELECT * FROM followers WHERE pk = $pk
I tried to SET id=null and VALUE (0), but both don't work.
All you have to do since you want all the columns except the identity is specify all the non-identity columns on the insert:
INSERT INTO [followers_lost] ([Column1],[column2]...{but not the identity
column})
SELECT [Column1],[column2]...{but not the identity column} FROM followers WHERE
pk = $pk
You can create the column and then update it:
SET #new_id=0;
UPDATE your_table
SET id = #new_id := #new_id + 1
where id = 0
OK based on your comment I think you are trying to take all or some of the fields from Followers except the PK and put them into Followers_Lost where they equal a certain PK. If you want multiple PK's you would need to change the where clause to an IN statement instead of an equal and adjust your values accordingly.
CREATE TABLE dbo.UAT_Followers_Lost (PK INT IDENTITY(1,1),DATA VARCHAR(50) )
CREATE TABLE dbo.UAT_Followers (PK INT IDENTITY(1,1),DATA VARCHAR(50) )
INSERT INTO dbo.UAT_Followers
(DATA)
SELECT 'Jan'
UNION ALL
SELECT 'Feb'
UNION ALL
SELECT 'Mar'
DECLARE #PK INT
SET #PK = 1
INSERT INTO dbo.UAT_Followers_Lost
(Data)
SELECT Data
FROM dbo.UAT_Followers
WHERE PK = #PK
I need to be able to check if a column exists and if it does then I want to SELECT from it.
I am trying lots of different variations but I'm not even sure if this is possible.
Here's my latest attempt:
SELECT
IF (EXISTS (SELECT `Period` AS `Period` FROM myview), `PERIOD`,
IF (EXISTS (SELECT `Country` AS `COUNTRY` FROM myview),`COUNTRY` FROM myview ;
Any ideas?
EDIT
I had seen the other question on here: MySQL, Check if a column exists in a table with SQL
But I still struggle with the if statement. I can check to see if the column exists using the answer in the question above. But my question is - how to execute a select statement from that column if the result is found to be true.
EDIT 2
The answer below indicates that I should use the BEGIN and END statement and this makes sense. However, my query complains at the first line. It says 'unexpected IF' - can anybody confirm if this is the right syntax fro MYSQL?
if( exists (SELECT *
FROM information_schema.COLUMNS
WHERE TABLE_SCHEMA = 'db_name'
AND TABLE_NAME = 'view_name'
AND COLUMN_NAME = 'column_name') )
begin
SELECT `column_name` FROM `view_name`
end
Thanks in advance.
This query will give you whether a column exists.
SELECT *
FROM information_schema.COLUMNS
WHERE
TABLE_SCHEMA = 'db_name'
AND TABLE_NAME = 'table_name'
AND COLUMN_NAME = 'column_name'
If you want to check if some columns exist then perform a select statement you need to first check your columns exist. Then perform the select:
if (exists (SELECT * FROM information_schema.COLUMNS WHERE TABLE_NAME = 'myview' AND COLUMN_NAME = 'Period') and exists (SELECT * FROM information_schema.COLUMNS WHERE TABLE_NAME = 'myview' AND COLUMN_NAME = 'Country'))
begin
select `Period`, `Country` from myview
end
If the IF condition is true, then you will execute anything inside the BEGIN and END.
I came across the same situation where I had some product tables created by sheets uploaded by users. Sometimes, the sheets did not have column named "obsolete", so I had to import all products from the sheet but not the obsolete ones.
I am not modifying my query based on the original question that was asked, but here is my solution:
SELECT
t2.model,
(
SELECT
COUNT(*) AS _count
FROM db.table t1
WHERE
`obsolete`=1
AND t1.model=t2.model
) AS `obsolete`
FROM (
SELECT
0 AS `obsolete`,
t3.model
FROM db.table t3
) t2
There are 2 most important parts in this query:
We are selecting 0 AS obsolete as dummy to fool MySql which will be used even if column does not exist when selecting COUNT(*).
We have named tables as t1 & t2 to match the column model as t1.model=t2.model.
how to write query for following request?
my table:
id designation
1 developer,tester,projectlead
1 developer
1 techlead
if id=1,designation="'developer'"
Then need to first,second records.Because 2 rows are having venkat.
if id=1,designation="'developer','techlead'" then need to get 3 records as result.
i wrote one service for inserting records to that table .so that i am maintaining one table to store all designation with same column with comas.
By using service if user pass id=1 designation="'developer','techlead'" then need to pull the above 3 records.so that i am maintaining only one table to save all designations
SP:
ALTER PROCEDURE [dbo].[usp_GetDevices]
#id INT,
#designation NVARCHAR (MAX)
AS
BEGIN
declare #idsplat varchar(MAX)
set #idsplat = #UserIds
create table #u1 (id1 varchar(MAX))
set #idsplat = 'insert #u1 select ' + replace(#idsplat, ',', ' union select ')
exec(#idsplat)
Select
id FROM dbo.DevicesList WHERE id=#id AND designation IN (select id1 from #u1)
END
You need to use the boolean operators AND and OR in conjunction with LIKE:
IF empid = 1 AND (empname LIKE '%venkat%' OR empname LIKE '%vasu%')
The above example will return all rows with empid equals 1 and empname containing venkat or vasu.
Apparently you need to create that query based on the input from user, this is just an example of how the finally query should look like.
Edit: Trying to do this within SqlServer can be quite hard so you should really change your approach on how you call the stored procedure. If you can't do this then you could try and split your designation parameter on , (the answers to this question show several ways of how to do this) and insert the values into a temporary table. Then you can JOIN on this temporary table with LIKE as described in this article.