Restrictions for SQL Statements

Maximum length of an SQL statement

? 16 KB (default 64 KB), defined by a support database parameter

Length of a label

32 characters

Numeric precision

38 digits

Number of tables

Unlimited

Number of columns in each table (with KEY)

1024

Number of columns in each table (without KEY)

1023

Number of primary key columns in each table

512

Number of columns in an index

16

Number of foreign key columns per table

16

Number of columns in an ORDER or GROUP clause

128

Number of columns in a SELECT statement

1023

Number of columns in an INSERT statement

1024

Number of columns in a results table

1023

Number of join tables in a SELECT statement

254

Number of JOIN predicates in a search condition

128

Number of triggers in each basis table

3

Number of indexes for each table

255

Number of referential CONSTRAINT definitions (foreign key dependencies) for each table

Unlimited

Number of references in each table

Unlimited

Number of rows in each table

Limited by the size of a database

Internal length of a table row

8088 bytes

Total of internal lengths of all key columns

1024 bytes

Total of internal lengths of all foreign key columns

1024 bytes

Total of internal lengths of all columns belonging to an index

1024 bytes

Internal length of a LONG column

2 GB

Length of the columns in an ORDER or GROUP clause

4016 bytes

Nested trigger levels

Unlimited

Nested subqueries

127

Number of join conditions in a WHERE clause of a SELECT statement

128

Number of correlated columns in an SQL statement

64

Number of correlated tables in an SQL statement

16

Number of parameters in an SQL statement

2000

See also:

Concepts of the Database System, Technical Restrictions