Summary: I am trying to add a Username to the db.username_table with a unique ID incremented by 1. However, I keep receiving an error 1111 related to my CASE statement. It should make the first User_ID 1, then all other new ones the max(user_id) +1. Any help would be greatly appreciated!
Background: This is for my first MySQL project - I have some experience with MS SQL that may be hindering me here. I googled many references and streamlined my code as much as possible, but the aggregate for the counter returns a 1111 error with an IF or with a CASE statement.
DELIMITER $$
CREATE PROCEDURE db.add_user
(
in new_username varchar(45)
)
begin
-- Set Counter ID
declare new_user_id int;
set new_user_id = if(max(db.username_table.User_ID) is null, 1, max(db.username_table.User_ID) + 1);
-- Add Username with Counter
insert into db.username_table (user_id, username)
values (new_user_id, new_username);
END$$
DELIMITER ;
Expected Result - Add a Username to the db.username_table with a unique ID incremented by 1.
Actual Result - Error 1111.
You are using the funtion MAX but not in SQL statements .. so the max of is used improperly . you need a select for retrive a MAX(db.username_table.User_ID.)
declare new_user_id int;
select case when
max(ifnull(db.username_table.User_ID,0)) = 0
then 1
else max(db.username_table.User_ID) + 1 end
INTO new_user_id
from your_table ;
but could you simply need an autoincrement column for User_id and avoid this SP
CREATE TABLE your_table (
User_ID int(11) NOT NULL AUTO_INCREMENT,
....
)
For the table bellow:
CREATE TABLE Persons (
ID int NOT NULL,
ModifiedDate datetime,
FirstName varchar(50),
LastName varchar(50),
EMail varchar(30),
PhoneNumber varchar(15),
PRIMARY KEY (ID)
);
You can write a query such as this:
INSERT INTO Persons(ModifiedDate, FirstName, LastName, EMail, PhoneNumber)
SELECT
CURRENT_TIMESTAMP - INTERVAL FLOOR(RAND()* 31536000) SECOND, -- random datetime up to -1 year
CHAR(FLOOR(RAND() * 26)+ ASCII('A')), -- random character between A-Z
CHAR(FLOOR(RAND() * 26)+ ASCII('A')),
CHAR(FLOOR(RAND() * 26)+ ASCII('a')), -- random character between a-z
CHAR(FLOOR(RAND() * 10)+ ASCII('0')) -- random character between 0-9
FROM any_table_with_1000_rows
LIMIT 1000
Any table with 1000 rows could be used. If there isn't one, you can join a table having n rows with itself to get n2 rows.
An easy way is to use https://www.mockaroo.com/ which is designed for that purpose. Create the columns you want and choose SQL as the output. It will make you a nice script.
You could also create an Excel spreadsheet to generate your SQL queries but it is a bit time consuming
Execute the following query, it will insert 1000 dummy rows
BEGIN
DECLARE #RowCount int = 1000,
#Index int = 1
WHILE (#Index <= #RowCount)
BEGIN
INSERT INTO Persons (ID, ModifiedDate, FirstName, LastName, EMail, PhoneNumber)
VALUES (#Index, getdate(), 'FirstName' + CAST(#Index AS varchar(10)), 'LastName' + CAST(#Index AS varchar(10)), 'EMail' + CAST(#Index AS varchar(10)), CAST(#Index AS varchar(10)))
SET #Index += 1
END
END
I have the table below. I'm looking for the both the max value in each column AND it's matching username (all values of NULL to be ignored).
A bunch of mad googling has lead me to believe I need to find the max values and then use a second query to find the matching username?
But is there a query that can return this in one go?
ID username Vale Jorge Andrea
-------------------------------------------
01 John 2 6 NULL
02 Ted NULL 0 0
03 Marcy NULL 2 1
Output would be...
John Jorge 6
John Vale 2
Marcy Andrea 1
There's different ways of looking at it, here's a table that gives a row for each username that has a matching max value:
SELECT
username
, IF (max_vale = t.vale, max_vale, NULL) AS for_vale
, IF (max_jorge = t.jorge, max_jorge, NULL) AS for_jorge
, IF (max_andrea = t.andrea, max_andrea, NULL) AS for_andrea
FROM (
SELECT
MAX(vale) AS max_vale
, MAX(jorge) AS max_jorge
, MAX(andrea) AS max_andrea
FROM t
) y
JOIN t ON (
t.vale = max_vale
OR t.jorge = max_jorge
OR t.andrea = max_andrea
)
http://sqlfiddle.com/#!9/58e37d/5
This gives:
username for_vale for_jorge for_andrea
----------------------------------------------
John 2 6 (null)
Marty (null) (null) 1
Basically, all I'm doing is selecting the specific column max values, then using that query as the source for another query that just looks at the MAX generated columns, and filters (IF()) based on the matches found.
This is one reasonably simple way of doing it... make a table of all the maximum values and join it to the usernames on matching the value with the max. Uses the fact that NULL isn't equal to anything. I haven't attempted to order the results but that is easy enough with adding an ORDER BY clause.
select username, name, COALESCE(mv.vale, mv.jorge, mv.Andrea) as value
from table1
join
(select 'Vale' as name, max(vale) as vale, NULL as jorge, NULL as andrea from table1
union ALL
select 'Jorge', NULL, max(jorge), NULL from table1
union all
select 'Andrea', NULL, NULL, max(andrea) from table1) mv
on table1.vale = mv.vale or table1.jorge = mv.jorge or table1.andrea = mv.andrea
Output
username name value
John Vale 2
John Jorge 6
Marcy Andrea 1
To extrapolate this to more columns is reasonably straightforward (if somewhat painful) e.g. to add a column called fred you would use (changes inside **):
select username, name, COALESCE(mv.vale, mv.jorge, mv.Andrea**, mf.fred**) as value
from table1
join
(select 'Vale' as name, max(vale) as vale, NULL as jorge, NULL as andrea**, NULL as fred** from table1
union ALL
select 'Jorge', NULL, max(jorge), NULL**, NULL** from table1
union all
select 'Andrea', NULL, NULL, max(andrea)**, NULL** from table1) mv
**union all
select 'Fred', NULL, NULL, max(fred), NULL from table1) mf**
on table1.vale = mv.vale or table1.jorge = mv.jorge or table1.andrea = mv.andrea **or table1.fred = mf.fred**
If you have access to stored procedures, you can also do it like this (in a much more flexible way in terms of columns)
DROP PROCEDURE IF EXISTS list_maxes;
DELIMITER //
CREATE PROCEDURE list_maxes(tname VARCHAR(20), column_list VARCHAR(1000))
BEGIN
DECLARE maxv INT DEFAULT 0;
DECLARE cpos INT;
DECLARE colname VARCHAR(20);
-- loop through the column names
WHILE (LENGTH(column_list) > 0)
DO
SET cpos = LOCATE(',', column_list);
IF (cpos > 0) THEN
SET colname = LEFT(column_list, cpos - 1);
SET column_list = SUBSTRING(column_list, cpos + 1);
ELSE
SET colname = column_list;
SET column_list = '';
END IF;
-- find the maximum value of this column
SET #getmax = CONCAT('SELECT MAX(', colname, ') INTO #maxv FROM Table1');
PREPARE s1 FROM #getmax;
EXECUTE s1;
DEALLOCATE PREPARE s1;
-- now find the user with the maximum value
SET #finduser = CONCAT("SELECT username, '", colname, "' AS name, ", colname, ' AS value FROM ', tname,' WHERE ', colname, ' = ', #maxv);
PREPARE s2 FROM #finduser;
EXECUTE s2;
DEALLOCATE PREPARE s2;
END WHILE;
END//
DELIMITER ;
CALL list_maxes('table1', 'Vale,Jorge,Andrea')
Output
John Vale 2
John Jorge 6
Marcy Andrea 1
This is quite long but working. I combine all columns into one table using UNION ALL. Then get the max value per surname. Join this to the original table using the surname and value. Order by value in descending order.
select tv.*
from( select surname, max(val) as maxval
from (
select username,'vale' as surname,vale as val
from tbl
union all
select username,'jorge' as surname,jorge
from tbl
union all
select username,'andrea' as surname,andrea
from tbl) tab
group by surname) tt
join (
select username,'vale' as surname,vale as val
from tbl
union all
select username,'jorge' as surname,jorge
from tbl
union all
select username,'andrea' as surname,andrea
from tbl) tv
on tt.surname=tv.surname and tt.maxval=tv.val
order by tv.val desc;
As a whole other way to resolve the request, we may look at the model, e.g., the fact that what appears to be domain content is represented as columns instead of rows. This is typical of a source aggregate query (pivot or rollup to get aggregated totals or groupings, for instance), but if the underlying data spreads out, should perhaps be based on the transactional integrity of that data source (the "spread out" underlying source).
Basically, I wonder why there are Vale, Jorge and Andrea columns at all in the database. This implies it's already been summarized.
So we may look at an alternate model that is notably easier to navigate for these purposes:
CREATE TABLE IF NOT EXISTS `user` (
`id` MEDIUMINT NOT NULL AUTO_INCREMENT,
`username` varchar(20) NOT NULL,
PRIMARY KEY (`id`)
) DEFAULT CHARSET=utf8;
CREATE TABLE IF NOT EXISTS `prospect` (
`id` MEDIUMINT NOT NULL AUTO_INCREMENT,
`name` varchar(20) NOT NULL,
PRIMARY KEY (`id`)
) DEFAULT CHARSET=utf8;
CREATE TABLE IF NOT EXISTS `aggregate` (
`id` MEDIUMINT NOT NULL AUTO_INCREMENT,
`user_id` int(6) unsigned NOT NULL,
`prospect_id` int(6) unsigned NOT NULL,
`total` int(6) unsigned NOT NULL,
PRIMARY KEY (`id`)
) DEFAULT CHARSET=utf8;
SELECT
user.username
, prospect.name
, MAX(aggregate.total) AS max_aggregate
FROM aggregate
JOIN user ON user_id = user.id
JOIN prospect ON prospect_id = prospect.id
GROUP BY username
This produces:
John Andrea 6
Marty Jorge 2
Ted Jorge 5
http://sqlfiddle.com/#!9/07ba0c/1
This may not be useful to you now, but as your experience grows and your experience with advanced querying evolves, this will make more sense. The main difficulty may be that the core data is already turned, making the querying more difficult because what you want is a different dimension than what you may have already derived.
Can anyone help me how to check duplicate values from multiple comma separated value. I have a customer table and in that one can insert multiple comma separated contact number and I want to check duplicate values from last five digits.For reference check screenshot attached and the required output is
contact_no. count
97359506775 -- 2
390558073039-- 1
904462511251-- 1
I would advise you to redesign your database schema, if possible. Your current database violates First Normal Form since your attribute values are not indivisible.
Create a table where id together with a single phone number constitutes a key, this constraint enforces that no duplicates occur.
I don't remember much but I will try to put the idea (it's something which I had used a long time ago):
Create a table value function which will take the id and phone number as input and then generate a table with id and phone numbers and return it.
Use this function in query passing id and phone number. The query is such that for each id you get as many rows as the phone numbers. CROSS APPLY/OUTER APPLY needs to be used.
Then you can check for the duplicates.
The function would be something like this:
CREATE FUNCTION udf_PhoneNumbers
(
#Id INT
,#Phone VARCHAR(300)
) RETURNS #PhonesTable TABLE(Id INT, Phone VARCHAR(50))
BEGIN
DECLARE #CommaIndex INT
DECLARE #CurrentPosition INT
DECLARE #StringLength INT
DECLARE #PhoneNumber VARCHAR(50)
SELECT #StringLength = LEN(#Phone)
SELECT #CommaIndex = -1
SELECT #CurrentPosition = 1
--index is 1 based
WHILE #CommaIndex < #StringLength AND #CommaIndex <> 0
BEGIN
SELECT #CommaIndex = CHARINDEX(',', #Phone, #CurrentPosition)
IF #CommaIndex <> 0
SELECT #PhoneNumber = SUBSTRING(#Phone, #CurrentPosition, #CommaIndex - #CurrentPosition)
ELSE
SELECT #PhoneNumber = SUBSTRING(#Phone, #CurrentPosition, #StringLength - #CurrentPosition + 1)
SELECT #CurrentPosition = #CommaIndex + 1
INSERT INTO #UsersTable VALUES(#Id, #PhoneNumber)
END
RETURN
END
Then run CROSS APPLY query:
SELECT
U.*
,UD.*
FROM yourtable U CROSS APPLY udf_PhoneNumbers(Userid, Phone) UD
This will give you the table on which you can run query to find duplicate.
I am trying to cast some bad data into proper data using CAST(column AS DECIMAL(7,2)), which works when just SELECTing, but once combined with an INSERT statement, the statement fails:
/* setup */
drop table if exists dst;
create table dst (
id int not null auto_increment
, columnA decimal(7,2)
, primary key (id)
);
drop table if exists src;
create table src (
id int not null auto_increment
, columnA varchar(255)
, primary key (id)
);
insert into src (columnA) values ('');
/* test */
/* This works as I would like it to*/
select CAST(columnA AS decimal(7,2)) from src; /* returns 0.00 */
/* This fails */
insert into dst (columnA)
select CAST(columnA AS decimal(7,2)) from src;
/*0 19 21:01:56 insert into dst (columnA)
select cast(columnA as decimal(7,2)) from src Error Code: 1366. Incorrect decimal value: '' for column '' at row -1 0.000 sec*/
Edit: this is a pared down reproduction example - the data I am
working with is much more varied than just an empty string - it might
also be a non-numeric string value or a numeric value that is outside
of the bounds of decimal(7,2) - in which the CAST statement works
the way I would like it to when only in a SELECT but fails when
trying to use them as part of the INSERT.
Am I doing something wrong, or is there another way to achieve what I am looking for?
I am using MYSQL 5.6.11 on WIN 7 x64
Set explicitly the value for the empty string with CASE or IF:
SELECT CASE WHEN columnA = '' THEN 0 ELSE CAST(columnA AS decimal(7,2)) END
FROM src;
SELECT IF(columnA <> '', CAST(columnA AS decimal(7,2)), 0)
FROM src;
Or use 2 SELECTs with UNION ALL :
SELECT CAST(columnA AS decimal(7,2))
FROM src
WHERE columnA <> ''
UNION ALL
SELECT 0
FROM src
WHERE columnA = '';
You can try using REGEXP to filter out any irregularities in source data:
INSERT INTO dst (columnA)
SELECT CAST(CASE
WHEN columnA REGEXP '^[0-9]{0,7}(\.[0-9]{0,2})$' THEN columnA
ELSE 0
END AS decimal(7,2))
FROM src;
SQL Fiddle Demo here