Alter all tables in database - mysql

Question

I would like to run a "Alter Table" on ALL the tables in my SQL databse:
ALTER TABLE test ADD CONSTRAINT [COLLUM_NAME] DEFAULT ((0)) FOR [COLLUM_NAME]
I know how to get all of the existing tables from the database:
SELECT TABLE_NAME
FROM INFORMATION_SCHEMA.TABLES
WHERE TABLE_TYPE = 'BASE TABLE'
or
USE DATABASE_NAME
GO
SELECT name
FROM sys.Tables
GO
But I don’t know how to combine these two.
In my database (50+ tables) all of the tables have 1 row in common.
and I would like to set a default value to all of these rows.

Answer 1

You can try to generate a command and execute it after.
You can do something like this:
SELECT CONCAT("Alter Table `", TABLE_SCHEMA,"`.`", TABLE_NAME, "` this is my default value change on the column") as MySQLCMD
FROM TABLES
And execute the retrieving.

Answer 2

If this is a one-off process that doesn't need to be automated then you could probably do worse than running something like the following and just copy/pasting the output:
select 'alter table ' + t.name + ' add constraint ' + c.name + ' default ((0)) for ' + c.name
from sysobjects t join syscolumns c on c.id = t.id
where t.xtype = 'U'

Answer 3

If u want use INFORMATION_SCHEMA
SELECT 'ALTER TABLE ' +t.TABLE_NAME+ ' ADD CONSTRAINT '
+c.COLUMN_NAME +' DEFAULT ((0)) FOR '+c.COLUMN_NAME
FROM INFORMATION_SCHEMA.TABLES t
INNER JOIN INFORMATION_SCHEMA.COLUMNS c on t.TABLE_NAME=c.TABLE_NAME
WHERE TABLE_TYPE = 'BASE TABLE'

Answer 4

set the 'COLUMN NAME' and execute, it will add a default constraint to setted column.
DECLARE #sql NVARCHAR(MAX) ;
DECLARE #LINEBREAK AS VARCHAR(2)
SET #LINEBREAK = CHAR(13) + CHAR(10)
SELECT #sql = COALESCE(#sql + ';' + #LINEBREAK, '') + 'ALTER TABLE '
+ QUOTENAME([TABLES].TABLE_NAME) + ' ADD CONSTRAINT ' + QUOTENAME([COLUMNS].COLUMN_NAME)
+ ' DEFAULT ((0)) FOR ' + QUOTENAME([COLUMNS].COLUMN_NAME)
FROM INFORMATION_SCHEMA.TABLES [TABLES]
INNER JOIN INFORMATION_SCHEMA.COLUMNS AS [COLUMNS] ON [TABLES].TABLE_NAME = [COLUMNS].TABLE_NAME
WHERE TABLE_TYPE = 'BASE TABLE'
AND [COLUMNS].[COLUMN_NAME] = 'COLUMN NAME'
PRINT #sql
EXEC sp_executesql #sql

Answer 5

My preferred way is to write a SP for this. I have some of these utility SPs in my databases and I alter them as needed to update things. Here's an example that changes the collation. You can see that by modifying the SET #S=... statement you can do any table alteration you like.
DECLARE table_name VARCHAR(255);
DECLARE end_of_tables INT DEFAULT 0;
DECLARE num_tables INT DEFAULT 0;
DECLARE cur CURSOR FOR
SELECT t.table_name
FROM information_schema.tables t
WHERE t.table_schema = DATABASE() AND t.table_type='BASE TABLE';
DECLARE CONTINUE HANDLER FOR NOT FOUND SET end_of_tables = 1;
OPEN cur;
tables_loop: LOOP
FETCH cur INTO table_name;
IF end_of_tables = 1 THEN
LEAVE tables_loop;
END IF;
SET num_tables = num_tables + 1;
SET #s = CONCAT('ALTER TABLE ' , table_name , ' CONVERT TO CHARACTER SET utf8 COLLATE utf8_unicode_ci');
PREPARE stmt FROM #s;
EXECUTE stmt;
END LOOP;
CLOSE cur;