Mysql uses stored procedures to determine whether a column (field) exists as a tutorial

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Determine whether the field exists:

DROP PROCEDURE IF EXISTS schema_change; DELIMITER / / CREATE PROCEDURE schema_change () BEGIN DECLARE CurrentDatabase VARCHAR (100); SELECT DATABASE () INTO CurrentDatabase;IF NOT EXISTS (SELECT * FROM information_schema.columns WHERE table_schema=CurrentDatabase AND table_name = 'rtc_order' AND column_name =' IfUpSend') THEN ALTER TABLE rtc_order ADD COLUMN `IfUpSend `BIT NOT NULL DEFAULT 0 COMMENT 'whether to upload or not'; END IF; END// DELIMITER; CALL schema_change ()

Mysql determines whether the field exists, and if so, modify the field:

DROP PROCEDURE IF EXISTS proc_tempPro;if (@ count > 0) THEN alter table table name change column `old column name ``new column name `varchar (30) comment 'field description'; end if;end;call proc_tempPro;DROP PROCEDURE IF EXISTS proc_tempPro

Determine whether the field exists through the stored procedure. If it does not exist, it will be added:

DROP PROCEDURE IF EXISTS pro_AddColumn;CREATE PROCEDURE pro_AddColumn () BEGINIF NOT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name='component' AND COLUMN_NAME='PRINT_CHECK_STATUS') THENALTER TABLE component ADD PRINT_CHECK_STATUS int (10) default 0 there end IF;IF NOT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_name='component' AND COLUMN_NAME='PRINT_CHECK_TIME') THENALTER TABLE component ADD PRINT_CHECK_TIME datetime NULL;END IF IF NOT EXISTS (SELECT 1 FROM information_schema.columns WHERE table_schema=podcloud AND table_name='component' AND COLUMN_NAME='PRINT_CHECK_BACK_REASON') THENALTER TABLE component ADD PRINT_CHECK_BACK_REASON varchar (500) default null;END IF;END;CALL pro_AddColumn;DROP PROCEDURE pro_AddColumn -DROP PROCEDURE IF EXISTS pro_AddIndex; DELIMITER CREATE PROCEDURE pro_AddIndex () BEGIN IF NOT EXISTS (SELECT * FROM information_schema.statistics WHERE table_schema=CurrentDatabase AND table_name = 'rtc_phototype' AND index_name =' index_name') THEN ALTER TABLE `rtc_ Phototype` ADD INDEX index_name (`imgtype`); END IF; END; DELIMITER; CALL pro_AddIndex (); Drop procedure pro_AddIndex

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