Rules and Restrictions for the QUALIFY Clause - Analytics Database - Teradata Vantage

SQL Data Manipulation Language

Deployment
VantageCloud
VantageCore
Edition
Enterprise
IntelliFlex
VMware
Product
Analytics Database
Teradata Vantage
Release Number
17.20
Published
June 2022
Language
English (United States)
Last Update
2024-04-05
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lifecycle
latest
Product Category
Teradata Vantage™
The rules and restrictions are:
  • You cannot specify LOB columns in a QUALIFY clause search condition.
  • You cannot specify an OR condition connected with a subquery in a QUALIFY clause search condition.

    The following query fails because of the OR condition connected with the subquery.

         SELECT RANK (column_1)
         FROM table_1
         QUALIFY column_1 IN (SELECT table_2.column_1
                              FROM table_2)
         OR table_1.column.1 = 10000;
  • When you specify a QUALIFY clause in a query, you must also specify a statistical function in one of the following locations within the query.
    • The select list of the SELECT clause
    • The grouping key of the GROUP BY clause
    • The search condition of the QUALIFY clause
  • If you specify the value for a row-level security constraint in a search condition, that value must be expressed in its encoded form.
  • The following rules apply to the use of the DEFAULT function as part of the search condition within a QUALIFY clause.
    • You can specify a DEFAULT function with a column name argument within a predicate. The database evaluates the DEFAULT function to the default value of the column specified as its argument and uses the value like a constant in the predicate.
    • You can specify a DEFAULT function without a column name argument within a predicate only if there is one column specification and one DEFAULT function as the terms on each side of the comparison operator within the expression.
    • Following existing comparison rules, a condition with a DEFAULT function used with comparison operators other than IS NULL or IS NOT NULL is unknown if the DEFAULT function evaluates to null.

      A condition other than IS NULL or IS NOT NULL with a DEFAULT function compared with a null evaluates to unknown.

      IF a DEFAULT function is used with … THEN the comparison is …
      IS NULL
      • TRUE if the default is null
      • Else it is FALSE
      IS NOT NULL
      • FALSE if the default is null
      • Else it is TRUE

    See Teradata Vantage™ - SQL Functions, Expressions, and Predicates, B035-1145 for more information about the DEFAULT function.

  • A SELECT statement that specifies the TOP n operator cannot also specify the QUALIFY clause.
  • You cannot specify a SAMPLE clause in a subquery used as a QUALIFY clause predicate.