Data conversion

When a discrepancy exists between the data types of two values, attempts to convert one of the data types. The process of converting a value from one data type to another is called data conversion.

The following list names a few common situations in which data conversion can occur:
Comparison
Data conversion can occur if you use a condition that compares two different types of values, such as comparing the contents of a zip-code column to an integer value.

For example, to compare a CHAR value and a numeric value, converts the CHAR value to a numeric value before it performs the comparison.

Fetching and inserting
Data conversion can occur if you fetch or insert values with host variables and database columns of different data types.
Arithmetic operations
Data conversion can occur if a numeric value of one data type operates on a value of a different data type.