看一下long 类型使用的一些限制:
You can reference LONG columns in SQL statements in these places: * SELECT lists
* SET clauses of UPDATE statements
* VALUES clauses of INSERT statements The use of LONG values are subject to some restrictions: * A table cannot contain more than one LONG column.
* LONG columns cannot appear in integrity constraints (except for
NULL and NOT NULL constraints). * LONG columns cannot be indexed.
* A procedure or stored function cannot accept a LONG argument.
* A stored function cannot return a LONG value.
* Within a single SQL statement, all LONG columns, sequences,
updated tables, and locked tables must be located on the same
database. Also, LONG columns cannot appear in certain parts of SQL statements: * WHERE, GROUP BY, ORDER BY, or CONNECT BY clauses or with the DISTINCT operator in SELECT statements
* SQL Functions (such as SUBSTR or INSTR)
* expressions or conditions
* select lists of queries containing GROUP BY clauses
* select lists of subqueries or queries combined by set operators
* select lists of CREATE TABLE AS SELECT statements
You can reference LONG columns in SQL statements in these places: * SELECT lists
* SET clauses of UPDATE statements
* VALUES clauses of INSERT statements The use of LONG values are subject to some restrictions: * A table cannot contain more than one LONG column.
* LONG columns cannot appear in integrity constraints (except for
NULL and NOT NULL constraints). * LONG columns cannot be indexed.
* A procedure or stored function cannot accept a LONG argument.
* A stored function cannot return a LONG value.
* Within a single SQL statement, all LONG columns, sequences,
updated tables, and locked tables must be located on the same
database. Also, LONG columns cannot appear in certain parts of SQL statements: * WHERE, GROUP BY, ORDER BY, or CONNECT BY clauses or with the DISTINCT operator in SELECT statements
* SQL Functions (such as SUBSTR or INSTR)
* expressions or conditions
* select lists of queries containing GROUP BY clauses
* select lists of subqueries or queries combined by set operators
* select lists of CREATE TABLE AS SELECT statements
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