Adding a new SQL column with a default value

开发者_JAVA百科I am looking for the syntax to add a column to a MySQL database with a default value of 0

Reference

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Try this:

ALTER TABLE table1 ADD COLUMN foo INT DEFAULT 0;

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From the documentation that you linked to:

ALTER [ONLINE | OFFLINE] [IGNORE] TABLE tbl_name
   alter_specification [, alter_specification] ...

alter_specification:
    ...
    ADD [COLUMN] (col_name column_definition,...)
    ...

To find the syntax for column_definition search a bit further down the page:

column_definition clauses use the same syntax for ADD and CHANGE as for CREATE TABLE. See Section 12.1.17, “CREATE TABLE Syntax”.

And from the linked page:

column_definition:  
   data_type [NOT NULL | NULL] [DEFAULT default_value]
   [AUTO_INCREMENT] [UNIQUE [KEY] | [PRIMARY] KEY]  
   [COMMENT 'string']  
   [COLUMN_FORMAT {FIXED|DYNAMIC|DEFAULT}]  
   [STORAGE {DISK|MEMORY|DEFAULT}]  
   [reference_definition]  

Notice the word DEFAULT there.

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Like this?

ALTER TABLE `tablename` ADD `new_col_name` INT NOT NULL DEFAULT 0;

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table users (user_id int unsigned PK, username varchar(32))

alter table users add column verified tinyint unsigned default 0

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Simply add default 0 at the end of your ALTER TABLE <table> ADD COLUMN <column> <type> statement

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This will work for ENUM type as default value

ALTER TABLE engagete_st.holidays add column `STATUS` ENUM('A', 'D') default 'A' AFTER `H_TYPE`;

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ALTER TABLE my_table ADD COLUMN new_field TinyInt(1) DEFAULT 0;

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You can try this,

ALTER TABLE table_name ADD column_name INT DEFAULT 0;

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If you are learning it's helpful to use a GUI like SQLyog, make the changes using the program and then see the History tab for the DDL statements that made those changes.

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Another useful keyword is FIRST and AFTER if you want to add it in a specific spot in your table.

ALTER TABLE `table1` ADD COLUMN `foo` AFTER `bar` INT DEFAULT 0;

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Try This :)

ALTER TABLE TABLE_NAME ADD COLUMN_NAME INT NOT NULL DEFAULT 0;