ERROR 1064 (42000) / Wrong SQL Syntax but i dont know why? [duplicate] - mysql

Question

I have this code:
ALTER TABLE `settings`
ADD COLUMN `multi_user` TINYINT(1) NOT NULL DEFAULT 1
And I want to alter this table only if this column doesn't exist.
I'm trying a lot of different ways, but nothing works:
ALTER TABLE `settings`
ADD COLUMN IF NOT EXISTS `multi_user` TINYINT(1) NOT NULL DEFAULT 1
With procedure:
DELIMITER $$
CREATE PROCEDURE Alter_Table()
BEGIN
DECLARE _count INT;
SET _count = ( SELECT COUNT(*)
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'settings' AND
COLUMN_NAME = 'multi_user');
IF _count = 0 THEN
ALTER TABLE `settings` ADD COLUMN `multi_user` TINYINT(1) NOT NULL DEFAULT 1
END IF;
END $$
DELIMITER ;
I got error in END IF, then in END and then in 1
How can I make this as simple as possible?

Answer 1

Use the following in a stored procedure:
IF NOT EXISTS( SELECT NULL
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'tablename'
AND table_schema = 'db_name'
AND column_name = 'columnname') THEN
ALTER TABLE `TableName` ADD `ColumnName` int(1) NOT NULL default '0';
END IF;

Answer 2

Use PREPARE/EXECUTE and querying the schema.
The host doesn't need to have permission to create or run procedures :
SET #dbname = DATABASE();
SET #tablename = "tableName";
SET #columnname = "colName";
SET #preparedStatement = (SELECT IF(
(
SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
WHERE
(table_name = #tablename)
AND (table_schema = #dbname)
AND (column_name = #columnname)
) > 0,
"SELECT 1",
CONCAT("ALTER TABLE ", #tablename, " ADD ", #columnname, " INT(11);")
));
PREPARE alterIfNotExists FROM #preparedStatement;
EXECUTE alterIfNotExists;
DEALLOCATE PREPARE alterIfNotExists;

Answer 3

Here is a solution that does not involve querying INFORMATION_SCHEMA, it simply ignores the error if the column does exist.
DROP PROCEDURE IF EXISTS `?`;
DELIMITER //
CREATE PROCEDURE `?`()
BEGIN
DECLARE CONTINUE HANDLER FOR SQLEXCEPTION BEGIN END;
ALTER TABLE `table_name` ADD COLUMN `column_name` INTEGER;
END //
DELIMITER ;
CALL `?`();
DROP PROCEDURE `?`;
P.S. Feel free to give it other name rather than ?

Answer 4

Add field if not exist:
CALL addFieldIfNotExists ('settings', 'multi_user', 'TINYINT(1) NOT NULL DEFAULT 1');
addFieldIfNotExists code:
DELIMITER $$
DROP PROCEDURE IF EXISTS addFieldIfNotExists
$$
DROP FUNCTION IF EXISTS isFieldExisting
$$
CREATE FUNCTION isFieldExisting (table_name_IN VARCHAR(100), field_name_IN VARCHAR(100))
RETURNS INT
RETURN (
SELECT COUNT(COLUMN_NAME)
FROM INFORMATION_SCHEMA.columns
WHERE TABLE_SCHEMA = DATABASE()
AND TABLE_NAME = table_name_IN
AND COLUMN_NAME = field_name_IN
)
$$
CREATE PROCEDURE addFieldIfNotExists (
IN table_name_IN VARCHAR(100)
, IN field_name_IN VARCHAR(100)
, IN field_definition_IN VARCHAR(100)
)
BEGIN
SET #isFieldThere = isFieldExisting(table_name_IN, field_name_IN);
IF (#isFieldThere = 0) THEN
SET #ddl = CONCAT('ALTER TABLE ', table_name_IN);
SET #ddl = CONCAT(#ddl, ' ', 'ADD COLUMN') ;
SET #ddl = CONCAT(#ddl, ' ', field_name_IN);
SET #ddl = CONCAT(#ddl, ' ', field_definition_IN);
PREPARE stmt FROM #ddl;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
END IF;
END;
$$
this is not original, but it IS copy-and-paste
source: javajon.blogspot.com/2012/10/

Answer 5

I used this approach (Without using stored procedure):
SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'tbl_name' AND COLUMN_NAME = 'column_name'
If it didnt return any rows then the column doesn't exists then alter the table:
ALTER TABLE tbl_name
ADD COLUMN column_name TINYINT(1) NOT NULL DEFAULT 1
Hope this helps.

Answer 6

hope this will help you
SELECT COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'tbl_name'
AND table_schema = 'db_name'
AND column_name = 'column_name'
or
delimiter '//'
CREATE PROCEDURE addcol() BEGIN
IF NOT EXISTS(
SELECT * FROM information_schema.COLUMNS
WHERE COLUMN_NAME='new_column' AND TABLE_NAME='tablename' AND TABLE_SCHEMA='the_schema'
)
THEN
ALTER TABLE `the_schema`.`the_table`
ADD COLUMN `new_column` TINYINT(1) NOT NULL DEFAULT 1;;
END IF;
END;
//
delimiter ';'
CALL addcol();
DROP PROCEDURE addcol;

Answer 7

$sql="SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME = 'Your_Table_Name' AND COLUMN_NAME = 'Your_New_Column_Name'";
$RESULT = mysqli_query($conn,$sql);
The abobe query return 0 if the column is not present in your table then you need to run alter query like below
if($RESULT){
$sqll="ALTER TABLE Your_table_Name ADD COLUMN Your_New_Column_Name varchar(20) NOT NULL DEFAULT 0";
}

Answer 8

SET #dbname = DATABASE();
SET #tablename = "table";
SET #columnname = "fieldname";
SET #preparedStatement = (SELECT IF(
(
SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
WHERE
(table_name = #tablename)
AND (table_schema = #dbname)
AND (column_name = #columnname)
) > 0,
"SELECT 1",
CONCAT("ALTER TABLE ", #tablename, " ADD ", #columnname, " DECIMAL(18,4) NULL;")
));
PREPARE alterIfNotExists FROM #preparedStatement;
EXECUTE alterIfNotExists;
DEALLOCATE PREPARE alterIfNotExists;

Answer 9

This below worked for me:
SELECT count(*)
INTO #exist
FROM information_schema.columns
WHERE table_schema = 'mydatabase'
and COLUMN_NAME = 'mycolumn'
AND table_name = 'mytable' LIMIT 1;
set #query = IF(#exist <= 0, 'ALTER TABLE mydatabase.`mytable` ADD COLUMN `mycolumn` MEDIUMTEXT NULL',
'select \'Column Exists\' status');
prepare stmt from #query;
EXECUTE stmt;

Answer 10

Sometimes it may happen that there are multiple schema created in a database.
So to be specific schema we need to target, so this will help to do it.
SELECT count(*) into #colCnt FROM information_schema.columns WHERE table_name = 'mytable' AND column_name = 'mycolumn' and table_schema = DATABASE();
IF #colCnt = 0 THEN
ALTER TABLE `mytable` ADD COLUMN `mycolumn` VARCHAR(20) DEFAULT NULL;
END IF;

Answer 11

Using this as an example:
https://dbabulletin.com/index.php/2018/03/29/best-practices-using-flyway-for-database-migrations/
DELIMITER $$
DROP PROCEDURE IF EXISTS upgrade_database_4_to_5 $$
CREATE PROCEDURE upgrade_database_4_to_5()
BEGIN
IF NOT EXISTS( (SELECT * FROM information_schema.COLUMNS WHERE TABLE_SCHEMA=DATABASE()
AND COLUMN_NAME='multi_user' AND TABLE_NAME='settings') ) THEN
ALTER TABLE `settings` ADD COLUMN `multi_user` TINYINT(1) NOT NULL DEFAULT 1;
END IF;
END $$
CALL upgrade_database_4_to_5() $$
DELIMITER ;