# Package adql.query.constraint

- Interface Summary
  Interface | Description
  --- | ---
  ADQLConstraint | An ADQL constraint (comparison, in, exists, ...) must implement this interface.

- Class Summary
  Class | Description
  --- | ---
  Between | It represents the BETWEEN predicate of SQL and ADQL.
  Comparison | Represents a comparison (numeric or not) between two operands.
  ConstraintsGroup | Represents a parenthesized list of constraints.
  Exists | Represents the predicate EXISTS of SQL and ADQL.
  In | It represents the IN predicate of SQL and ADQL.
  IsNull | Represents a comparison between a column to the NULL value.
  NotConstraint | Lets apply the logical operator NOT on any constraint.

- Enum Summary
  Enum | Description
  --- | ---
  ComparisonOperator | Gathers all comparison operators (numeric or not).