Parameter Data Types

Even though each parameter specified with SQLBindParameter is defined using a SQL data type, the parameters in a SQL statement have no intrinsic data type. Therefore, parameter markers can be included in a SQL statement only if their data types can be inferred from another operand in the statement. For example, in an arithmetic expression such as ? + COLUMN1, the data type of the parameter can be inferred from the data type of the named column represented by COLUMN1. An application cannot use a parameter marker if the data type cannot be determined.

The following table describes how a data type is determined for several types of parameters, in accordance with SQL-92. For a more comprehensive specification on inferring the parameter type when other SQL clauses are used, see the SQL-92 specification.

Location of parameter	Assumed data type
One operand of a binary arithmetic or comparison operator	Same as the other operand
The first operand in a BETWEEN clause	Same as the second operand
The second or third operand in a BETWEEN clause	Same as the first operand
An expression used with IN	Same as the first value or the result column of the subquery
A value used with IN	Same as the expression or the first value if there is a parameter marker in the expression
A pattern value used with LIKE	VARCHAR
An update value used with UPDATE	Same as the update column