Selects

Specifying A Select Clause

You may not always want to select all columns from a database table. You can influence the select list of a query with the following methods.

Individual columns can contain fully-qualified names (some_table.some_column), table aliases (alias.some_column), and even set column aliases themselves (some_column AS c). The columns argument can be a single column, a list of columns (comma-separated), or an array of columns.

select

When calling select any previous columns are discarded. If you want to incrementally select columns, use the addSelect method.

If you pass no columns to this method, it will default to "*".

query.select( [ "fname AS firstName", "age" ] ).from( "users" );

SELECT `name` AS `firstName`, `age` FROM `users`

distinct

Calling distinct will cause the query to be executed with the DISTINCT keyword.

query.select( "username" ).distinct().from( "users" );

SELECT DISTINCT `username` FROM `users`

addSelect

This method adds the columns passed to it to the currently selected columns.

query.select( [ "fname AS firstName", "age" ] ).from( "users" );

SELECT `name` AS `firstName`, `age` FROM `users`

selectRaw

A shortcut to use a raw expression in the select clause.

The expression is added to the other already selected columns.

(To learn more about raw and expressions, check out the docs on Raw Expressions.)

query.selectRaw( "YEAR(birthdate) AS birth_year" ).from( "users" );

SELECT YEAR(birthdate) AS birth_year FROM `users`

subSelect

The method lets you pass either a callback or a QueryBuilder instance to be used as a subselect expression. If a callback is passed it will be passed a new query instance as the only parameter.

The subselect is added to the other already selected columns.

query.subSelect( "last_login_date", function( q ) {
    q.selectRaw( "MAX(created_date)" )
        .from( "logins" )
        .whereColumn( "users.id", "logins.user_id" );
} ) ).from( "users" );

SELECT (
    SELECT MAX(created_date)
    FROM `logins`
    WHERE `users`.`id` = `logins`.`user_id`
) AS `last_login_date`
FROM `users