Alter

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Alter
The alter method loads up an existing table in order to make modifications. These modifications may include adding, renaming, or dropping columns and constraints.
To begin altering an existing table, call the alter method off of the SchemaBuilder. This method takes a callback as the second parameter that is passed a Blueprint object, much like the create method.
Argument
Type
Required
Default
Description
table
string
true
​
The name of the table to alter.
callback
function
true
​
A callback function used to define the alterations to the table. It is passed a Blueprint as the only argument.
options
struct
false
{}
Options to pass to queryExecute.
execute
boolean
false
true
Run the query immediately after building it.
Calling multiple methods inside a single alter callback creates multiple SQL statements to be executed. qb takes care of this execution for you by default.
The following methods off of Blueprint let you modify the table inside the callback:
addColumn
Add a new column to an existing table. Takes a Column instance as the only argument.
Any instance of Column is valid like those returned by the column methods (integer, string, etc.) as well as the column modifier methods (unsigned, nullable, etc.).
Argument
Type
Required
Default
Description
column
Column
true
​
A column object to add to the table.
Example:
SchemaBuilder
1
schema.alter( "users", function( table ) {
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    table.addColumn( table.boolean( "is_active" ) );
3
} );
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SQL (MySQL)
1
ALTER TABLE `users` ADD `is_active` TINYINT(1) NOT NULL
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raw
An escape hatch to directly insert any sql in to the statement.
Argument
Type
Required
Default
Description
sql
string
true
​
The sql to insert directly into the statement.
Example:
SchemaBuilder
1
schema.alter( "registrars", function ( table ) {
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    table.addColumn(
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        table.raw( "HasDNSSecAPI bit NOT NULL CONSTRAINT DF_registrars_HasDNSSecAPI DEFAULT (0)" )
4
    );
5
} );
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SQL (MySQL)
1
ALTER TABLE `registrars`
2
ADD HasDNSSecAPI bit NOT NULL
3
CONSTRAINT DF_registrars_HasDNSSecAPI DEFAULT (0)
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dropColumn
Drop a column on an existing table.
Argument
Type
Required
Default
Description
name
string
true
​
The name of the column to drop.
Example:
SchemaBuilder
1
schema.alter( "users", function( table ) {
2
    table.dropColumn( "username" );
3
} );
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SQL (MySQL)
1
ALTER TABLE `users` DROP COLUMN `username`
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modifyColumn
Modify an existing column on a table.
Argument
Type
Required
Default
Description
name
string
true
​
The name of the column to modify.
column
Column
true
​
A column object to replace the named column.
Example:
SchemaBuilder
1
schema.alter( "users", function( table ) {
2
    table.modifyColumn( "name", table.string( "username" ) );
3
} );
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SQL (MySQL)
1
ALTER TABLE `users` CHANGE `name` `username` VARCHAR(255) NOT NULL
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renameColumn
Rename a column on a table. A full Column instance is required as the second argument for Grammars that need to redeclare the column definition when renaming.
Argument
Type
Required
Default
Description
name
string
true
​
The current name of a column.
column
Column
true
​
A column object with the new column name and definition.
Example:
SchemaBuilder
1
schema.alter( "users", function( table ) {
2
    table.renameColumn( "name", table.string( "username" ) );
3
} );
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SQL (MySQL)
1
ALTER TABLE `users` CHANGE `name` `username` VARCHAR(255) NOT NULL
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addConstraint
Add an index or key to an existing table. Any TableIndex instance is valid, like those created by the index methods (unique, index, primaryKey, etc.).
Argument
Type
Required
Default
Description
constraint
TableIndex
true
​
The TableIndex instance to add to the table.
Example:
SchemaBuilder
1
schema.alter( "users", function( table ) {
2
    table.addConstraint( table.unique( "username" ) );
3
} );
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SQL (MySQL)
1
ALTER TABLE `users` ADD CONSTRAINT `unq_users_username` UNIQUE (`username`)
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dropConstraint
Drop an existing table constraint.
Argument
Type
Required
Default
Description
name
string OR TableIndex
true
​
The name of the constraint to drop. You can alternatively pass a TableIndex instance to use the dynamic name generated.
Example:
SchemaBuilder
1
schema.alter( "users", function( table ) {
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    table.dropConstraint( "unq_users_full_name" );
3
    table.dropConstraint( table.unique( "username" ) );
4
} );
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SQL (MySQL)
1
ALTER TABLE `users` DROP INDEX `unq_users_full_name`
2
ALTER TABLE `users` DROP INDEX `unq_users_username`
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renameConstraint
Rename an existing table constraint.
Argument
Type
Required
Default
Description
oldName
string OR TableIndex
true
​
The old or current name of the constraint to rename. You can alternatively pass a TableIndex instance to use the dynamic name generated.
newName
string OR TableIndex
true
​
The new name of the constraint.  You can alternatively pass a TableIndex instance to use the dynamic name generated.
Example:
SchemaBuilder
1
schema.alter( "users", function( table ) {
2
    table.renameConstraint( "unq_users_first_name_last_name", "unq_users_full_name" );
3
} );
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SQL (MySQL)
1
ALTER TABLE `users` RENAME INDEX `unq_users_first_name_last_name` TO `unq_users_full_name`
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renameTable
Rename an existing table.
Argument
Type
Required
Default
Description
oldName
string
true
​
The old or current name of the table to rename.
newName
string
true
​
The new name of the table.
Example:
SchemaBuilder
1
schema.renameTable( "workers", "employees" );
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SQL (MySQL)
1
RENAME TABLE `workers` TO `employees`
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rename
An alias for renameTable.
Argument
Type
Required
Default
Description
oldName
string
true
​
The old or current name of the table to rename.
newName
string
true
​
The new name of the table.
Example:
SchemaBuilder
1
schema.rename( "workers", "employees" );
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SQL (MySQL)
1
RENAME TABLE `workers` TO `employees`
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