> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/kysely-org/kysely/llms.txt
> Use this file to discover all available pages before exploring further.

# AlterTableBuilder

> Builder for altering table definitions in Kysely

The `AlterTableBuilder` class is used to construct `ALTER TABLE` queries. It provides a fluent API for modifying tables, adding or dropping columns, and managing constraints.

## Methods

### renameTo

Renames the table.

```ts theme={null}
renameTo(newTableName: string): AlterTableExecutor
```

<ParamField path="newTableName" type="string" required>
  The new name for the table
</ParamField>

<ResponseField name="returns" type="AlterTableExecutor">
  An executor for the alter table query
</ResponseField>

### setSchema

Sets the schema for the table.

```ts theme={null}
setSchema(newSchema: string): AlterTableExecutor
```

<ParamField path="newSchema" type="string" required>
  The new schema for the table
</ParamField>

<ResponseField name="returns" type="AlterTableExecutor">
  An executor for the alter table query
</ResponseField>

### alterColumn

Alters a column in the table.

```ts theme={null}
alterColumn(
  column: string,
  alteration: AlterColumnBuilderCallback
): AlterTableColumnAlteringBuilder
```

<ParamField path="column" type="string" required>
  The name of the column to alter
</ParamField>

<ParamField path="alteration" type="AlterColumnBuilderCallback" required>
  A callback that receives an AlterColumnBuilder and returns modifications
</ParamField>

<ResponseField name="returns" type="AlterTableColumnAlteringBuilder">
  A builder for additional column alterations
</ResponseField>

### dropColumn

Drops a column from the table.

```ts theme={null}
dropColumn(column: string): AlterTableColumnAlteringBuilder
```

<ParamField path="column" type="string" required>
  The name of the column to drop
</ParamField>

<ResponseField name="returns" type="AlterTableColumnAlteringBuilder">
  A builder for additional column alterations
</ResponseField>

### renameColumn

Renames a column.

```ts theme={null}
renameColumn(
  column: string,
  newColumn: string
): AlterTableColumnAlteringBuilder
```

<ParamField path="column" type="string" required>
  The current name of the column
</ParamField>

<ParamField path="newColumn" type="string" required>
  The new name for the column
</ParamField>

<ResponseField name="returns" type="AlterTableColumnAlteringBuilder">
  A builder for additional column alterations
</ResponseField>

### addColumn

Adds a new column to the table.

```ts theme={null}
addColumn(
  columnName: string,
  dataType: DataTypeExpression,
  build?: ColumnDefinitionBuilderCallback
): AlterTableColumnAlteringBuilder
```

<ParamField path="columnName" type="string" required>
  The name of the column to add
</ParamField>

<ParamField path="dataType" type="DataTypeExpression" required>
  The data type of the column
</ParamField>

<ParamField path="build" type="ColumnDefinitionBuilderCallback">
  Optional callback to configure the column definition
</ParamField>

<ResponseField name="returns" type="AlterTableColumnAlteringBuilder">
  A builder for additional column alterations
</ResponseField>

### modifyColumn

Creates an `ALTER TABLE MODIFY COLUMN` query.

The `MODIFY COLUMN` statement is only implemented by MySQL and Oracle. On other databases you should use the `alterColumn` method.

```ts theme={null}
modifyColumn(
  columnName: string,
  dataType: DataTypeExpression,
  build?: ColumnDefinitionBuilderCallback
): AlterTableColumnAlteringBuilder
```

<ParamField path="columnName" type="string" required>
  The name of the column to modify
</ParamField>

<ParamField path="dataType" type="DataTypeExpression" required>
  The new data type for the column
</ParamField>

<ParamField path="build" type="ColumnDefinitionBuilderCallback">
  Optional callback to configure the column definition
</ParamField>

<ResponseField name="returns" type="AlterTableColumnAlteringBuilder">
  A builder for additional column alterations
</ResponseField>

### addUniqueConstraint

Adds a unique constraint for one or more columns.

See [CreateTableBuilder.addUniqueConstraint](/api/create-table-builder#adduniqueconstraint) for more details.

```ts theme={null}
addUniqueConstraint(
  constraintName: string,
  columns: string[],
  build?: UniqueConstraintNodeBuilderCallback
): AlterTableExecutor
```

<ParamField path="constraintName" type="string" required>
  The name of the constraint
</ParamField>

<ParamField path="columns" type="string[]" required>
  The columns to include in the unique constraint
</ParamField>

<ParamField path="build" type="UniqueConstraintNodeBuilderCallback">
  Optional callback to configure the constraint
</ParamField>

<ResponseField name="returns" type="AlterTableExecutor">
  An executor for the alter table query
</ResponseField>

### addCheckConstraint

Adds a check constraint.

See [CreateTableBuilder.addCheckConstraint](/api/create-table-builder#addcheckconstraint) for more details.

```ts theme={null}
addCheckConstraint(
  constraintName: string,
  checkExpression: Expression<any>,
  build?: CheckConstraintBuilderCallback
): AlterTableExecutor
```

<ParamField path="constraintName" type="string" required>
  The name of the constraint
</ParamField>

<ParamField path="checkExpression" type="Expression<any>" required>
  The check expression
</ParamField>

<ParamField path="build" type="CheckConstraintBuilderCallback">
  Optional callback to configure the constraint
</ParamField>

<ResponseField name="returns" type="AlterTableExecutor">
  An executor for the alter table query
</ResponseField>

### addForeignKeyConstraint

Adds a foreign key constraint.

Unlike [CreateTableBuilder.addForeignKeyConstraint](/api/create-table-builder#addforeignkeyconstraint), this method returns the constraint builder and doesn't take a callback as the last argument. This is because you can only add one column per `ALTER TABLE` query.

```ts theme={null}
addForeignKeyConstraint(
  constraintName: string,
  columns: string[],
  targetTable: string,
  targetColumns: string[],
  build?: ForeignKeyConstraintBuilderCallback
): AlterTableAddForeignKeyConstraintBuilder
```

<ParamField path="constraintName" type="string" required>
  The name of the constraint
</ParamField>

<ParamField path="columns" type="string[]" required>
  The columns in this table
</ParamField>

<ParamField path="targetTable" type="string" required>
  The target table name
</ParamField>

<ParamField path="targetColumns" type="string[]" required>
  The columns in the target table
</ParamField>

<ParamField path="build" type="ForeignKeyConstraintBuilderCallback">
  Optional callback to configure the constraint
</ParamField>

<ResponseField name="returns" type="AlterTableAddForeignKeyConstraintBuilder">
  A builder for the foreign key constraint
</ResponseField>

### addPrimaryKeyConstraint

Adds a primary key constraint for one or more columns.

See [CreateTableBuilder.addPrimaryKeyConstraint](/api/create-table-builder#addprimarykeyconstraint) for more details.

```ts theme={null}
addPrimaryKeyConstraint(
  constraintName: string,
  columns: string[],
  build?: PrimaryKeyConstraintBuilderCallback
): AlterTableExecutor
```

<ParamField path="constraintName" type="string" required>
  The name of the constraint
</ParamField>

<ParamField path="columns" type="string[]" required>
  The columns to include in the primary key
</ParamField>

<ParamField path="build" type="PrimaryKeyConstraintBuilderCallback">
  Optional callback to configure the constraint
</ParamField>

<ResponseField name="returns" type="AlterTableExecutor">
  An executor for the alter table query
</ResponseField>

### dropConstraint

Drops a constraint from the table.

```ts theme={null}
dropConstraint(constraintName: string): AlterTableDropConstraintBuilder
```

<ParamField path="constraintName" type="string" required>
  The name of the constraint to drop
</ParamField>

<ResponseField name="returns" type="AlterTableDropConstraintBuilder">
  A builder for dropping constraints
</ResponseField>

### renameConstraint

Renames a constraint.

```ts theme={null}
renameConstraint(
  oldName: string,
  newName: string
): AlterTableDropConstraintBuilder
```

<ParamField path="oldName" type="string" required>
  The current name of the constraint
</ParamField>

<ParamField path="newName" type="string" required>
  The new name for the constraint
</ParamField>

<ResponseField name="returns" type="AlterTableDropConstraintBuilder">
  A builder for the constraint operation
</ResponseField>

### addIndex

Adds an index to the table.

```ts theme={null}
addIndex(indexName: string): AlterTableAddIndexBuilder
```

<ParamField path="indexName" type="string" required>
  The name of the index to add
</ParamField>

<ResponseField name="returns" type="AlterTableAddIndexBuilder">
  A builder for creating the index
</ResponseField>

#### Examples

```ts theme={null}
db.schema.alterTable('person')
  .addIndex('person_email_index')
  .column('email')
  .unique()
  .execute()
```

Generated SQL (MySQL):

```sql theme={null}
alter table `person` add unique index `person_email_index` (`email`)
```

### dropIndex

Drops an index from the table.

```ts theme={null}
dropIndex(indexName: string): AlterTableExecutor
```

<ParamField path="indexName" type="string" required>
  The name of the index to drop
</ParamField>

<ResponseField name="returns" type="AlterTableExecutor">
  An executor for the alter table query
</ResponseField>

#### Examples

```ts theme={null}
db.schema.alterTable('person')
  .dropIndex('person_email_index')
  .execute()
```

Generated SQL (MySQL):

```sql theme={null}
alter table `person` drop index `test_first_name_index`
```

### \$call

Calls the given function passing `this` as the only argument.

See [CreateTableBuilder.\$call](/api/create-table-builder#call) for more details.

```ts theme={null}
$call<T>(func: (qb: this) => T): T
```

<ParamField path="func" type="(qb: this) => T" required>
  A function that receives the builder and returns a value
</ParamField>

<ResponseField name="returns" type="T">
  The return value of the provided function
</ResponseField>