4/7/2023 0 Comments Alter table add column![]() ![]() The SQL ALTER TABLE statement can be used to do both of the above two things. ![]() If you need to use literal single-quotes inside a string, use two single-quote characters for each one. Deleting specific column in an existing table. 'ALTER TABLE `table_schema`.`user` ADD COLUMN username3 VARCHAR(50) NOT NULL DEFAULT ''''',Īlso notice I replaced the quotes in your ALTER TABLE statement. The "else" part of this expression is DO TRUE which is a statement that will serve as a no-op. Then you can assign the result to a string variable, and run that as a new dynamic SQL statement. With this, you can test a condition and return one or the other expression. This is the reason you get a syntax error as soon as you use the token IF in an SQL query directly, but you don't get the error if you use it in a stored procedure.īut MySQL also has an IF() function you can use for scalar expressions. END block, and that must be in a stored program. This means you can't use these statements as direct SQL. Youll need the right column type for the other column here: ALTER TABLE table MODIFY created DATETIME AFTER extracol. Then use another alter command to move the previous column after the new one. The other compound statements mentioned by this sentence include IF. First insert the new column after the column we really want it before: ALTER TABLE table ADD extracol VARCHAR (255) AFTER created. END compound statement and other statements that can be used in the body of stored programs: Stored procedures and functions, triggers, and events. This section describes the syntax for the BEGIN. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |