Table Constraints

Constraints help to ensure that the data entered in the table is correct. Constraints also provide information to SAP Sybase IQ that boosts performance.

SAP Sybase IQ does not allow the creation of a check constraint that it cannot evaluate, such as those composed of user-defined functions, proxy tables, or non-SAP Sybase IQ tables. Constraints that cannot be evaluated are detected the first time the table on which the check constraint is defined is loaded or modified.

• Creating a Column Check Constraint
  A column check constraint enforces a specified condition on a column. Add a column check constraint to a table using the Create Constraint Wizard.
• Creating a Foreign Key Constraint
  A foreign key constraint enforces a restriction on a column specifying how the data in one table relates to the data in another table, or the same table. Add a foreign key constraint to the table using the Create Constraint Wizard.
• Creating a Table Check Constraint
  A table check constraint ensures that no row in a table violates the constraint, which may include more than one column in its specification.
• Creating a Unique Constraint
  The unique constraint specifies that one or more columns uniquely identify each row in the table.
• Deleting a Table or Column Check Constraint
  Delete a table or column check constraint from a table.
• Deleting a Primary, Foreign, or Unique Key Constraint
  Delete a primary, foreign, or unique key constraint from a table.
• Rebuilding a Unique, Primary or Foreign Key Constraint
  Rebuild a unique, primary, or foreign key constraint on a system store (IQ catalog store) table.
• Validating a Unique, Primary or Foreign Key Constraint
  Check the validity of unique, primary, or foreign key constraint on system store (IQ catalog store) table.
• Generating Constraint DDL Commands
  Display the data description language SQL code for adding a constraint to a table. The DDL can be a useful reference and training tool.
• Viewing or Modifying Constraint Properties
  View constraint details or change the constraint details and constraint definition of an existing constraint.
• Table Constraints Privilege Summary
  A list of the system privileges and object permissions required to complete the various table constraints tasks.