[Home](./index.md) > [@firebase/database](./database.md) > [QueryConstraintType](./database.queryconstrainttype.md) ## QueryConstraintType type Describes the different query constraints available in this SDK. Signature: ```typescript export declare type QueryConstraintType = 'endAt' | 'endBefore' | 'startAt' | 'startAfter' | 'limitToFirst' | 'limitToLast' | 'orderByChild' | 'orderByKey' | 'orderByPriority' | 'orderByValue' | 'equalTo'; ```