Third, use the FIRST or AFTER column_name option to determine the new position of the column. Second, specify the column name and the new name followed by column definition after the CHANGE COLUMN keywords. First, specify the name of the table to which the column belongs. To rename a column, you use the following statement: ALTER TABLE table_nameĬHANGE COLUMN original_name new_name column_definition Third, show the new column list of the vehicles table to verify the modifications: MySQL ALTER TABLE – Rename a column in a table Second, modify the color column by setting the maximum length to 20, removing the NOT NULL constraint, and changing its position to appear after the make column. First, modify the data type of the year column from INT to SMALLINT. MODIFY color VARCHAR( 20) NULL AFTER make Second, use the ALTER TABLE MODIFY statement to modify multiple columns: ALTER TABLE vehicles The following statement allows you to modify multiple columns: ALTER TABLE table_nameįirst, show the current columns of the vehicles table: Then, modify the note column: ALTER TABLE vehiclesįinally, show the column list of the vehicles table to verify the change: DESCRIBE vehicles Ĭode language: SQL (Structured Query Language) ( sql ) 2) Modify multiple columns Suppose that you want to change the note column a NOT NULL column with a maximum of 100 characters.įirst, show the column list of the vehicles table: DESCRIBE vehicles It’s a good practice to view the attributes of a column before modifying it. Here is the basic syntax for modifying a column in a table: ALTER TABLE table_name This statement shows the new structure of the vehicles table: DESCRIBE vehicles Ĭode language: SQL (Structured Query Language) ( sql ) MySQL ALTER TABLE – Modify columns 1) Modify a column To add multiple columns to a table, you use the following form of the ALTER TALE ADD statement: ALTER TABLE table_nameįor example, this statement adds two columns color and note to the vehicles table: ALTER TABLE vehicles This statement shows the column list of the vehicles table: DESCRIBE vehicles Īs shown clearly from the output, the column model has been added to the vehicles table. The following example uses the ALTER TABLE ADD statement to add a column at the end of the vehicles table: ALTER TABLE vehicles If you omit this clause, the column is appended at the end of the column list of the table. 
You can add a column after an existing column ( ATER column_name) or as the first column ( FIRST). FIRST | AFTER column_name specify the position of the new column in the table.column_definition– specify the datatype, maximum size, and column constraint of the new column.new_column_name – specify the name of the new column.table_name – specify the name of the table that you want to add a new column or columns after the ALTER TABLE keywords.To add a column to a table, you use the ALTER TABLE ADD syntax: ALTER TABLE table_nameĬode language: SQL (Structured Query Language) ( sql ) The ALTER TABLE ADD statement allows you to add one or more columns to a table. Let’s create a table named vehicles for the demonstration: CREATE TABLE vehicles (Ĭode language: SQL (Structured Query Language) ( sql ) MySQL ALTER TABLE – Add columns to a table
Alter sql how to#
Summary: in this tutorial, you will learn how to use the MySQL ALTER TABLE statement to add a column, alter a column, rename a column, drop a column and rename a table.
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