ABAP Keyword Documentation → ABAP - Reference → Processing External Data → ABAP - Database Accesses → Open SQL → Open SQL - Read Accesses → SELECT → SELECT - cond → WHERE - sql_cond
sql_cond - subquery
Other versions: 7.31 | 7.40 | 7.54
Syntax
... ( SELECT result
FROM source
[WHERE sql_cond]
[GROUP BY
group] [HAVING group_cond] ) ...
Wirkung
A subquery is a SELECT statement in parenthesis in which all additions except
SINGLE,
INTO, and ORDER
BY can be used. A subquery with a single-column resulting set, in other words, the specification
of the columns in the
expression result of the subquery is limited to one column or to an
aggregate expression, is known as a scalar subquery.
A subquery can be used within the following logical expressions sql_cond of the WHERE conditions for a subquery:
Subqueries can be nested by using subqueries in the WHERE conditions of a
subquery. In nested subqueries, the columns specified in the WHERE conditions
are searched inside out, though the columns of inner subqueries conceal columns with the same name in outer subqueries.
A subquery that uses columns from the surrounding SELECT statement in its
WHERE condition, is known as a correlated subquery. It must be possible to
assign the column uniquely to a database table or view in the surrounding SELECT
statement. A correlated subquery is evaluated for each individual line of the resulting set in the surrounding SELECT statement.
A maximum of 10 SELECT statements are permitted within one ABAP statement,
in other words the SELECT itself and a maximum of 9 other subqueries. This
restriction is independent of whether the subqueries are nested or occur in different logical expressions of the WHERE condition.
Notes
- Subqueries cannot be used when accessing pool tables or cluster tables.
- With a correlated subquery, a projection view cannot be accessed in the surrounding
SELECTstatement.
- If a subquery is used, the Open SQL statement bypasses SAP buffering.