# Schema queries

This reference covers the usage of schema queries in TypeQL. These queries can be only executed in schema transactions.

## [](#_query_types)Query types

[Define query](define/index.md)

Used to add new types, capabilities, annotations, or functions to the schema.

[Undefine query](undefine/index.md)

Used to remove existing types, capabilities, annotations, or functions from the schema.

[Redefine query](redefine/index.md)

Used to modify existing types, capabilities, annotations, or functions in the schema.

[Data and query model](../data-model/index.md) [Define](define/index.md)

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