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DEFAULT
It is used to set default value for specified column. There is possibility of setting default value while creating new table or for existing table with ALTER keyword.Syntax for setting default value during creating new table
CREATE `table_name`
(
`column_name1` data_type [DEFAULT 'default_value'],
`column_name2` data_type [DEFAULT 'default_value']
)
Syntax for setting default value for existing table
ALTER TABLE `table_name`
ALTER [COLUMN] `column_name`
SET DEFAULT 'default_value'
Syntax for deleting DEFAULT for existing table
ALTER TABLE `table_name`
ALTER [COLUMN] `column_name`
DROP DEFAULT 'default_value'
In MySQL after ALTER there heve to be placed name of modified column, in SQL Server / Oracle / MS Access
before giving column name there is used ALTER COLUMN keyword.
Example
Create `people` table for name, surname and visitors counter with default value equals zero.
query
CREATE TABLE `people`
{
`name` text
`surname` text
`counter` int DEFAULT 0
}
Now add data of Mr Jan Kowalski to existing table.
query
INSERT INTO `people` (`name`,`surname`)
VALUES ('Jan','Kowalski')
}
result
| name | surname | counter |
|---|---|---|
| Jan | Kowalski | 0 |
