## 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