The previous example included an indicator variable that identifies any row in which the value of the comm column (when returned by the server) was NULL. An indicator variable is an extra host variable that denotes if the content of the preceding variable is NULL or truncated. The indicator variable is populated when the contents of a row are stored. An indicator variable may contain the following values:
The value returned by the server was not NULL, and was not truncated. When including an indicator variable in an INTO clause, you are not required to include the optional INDICATOR keyword.You may omit an indicator variable if you are certain that a query will never return a NULL value into the corresponding host variable. If you omit an indicator variable and a query returns a NULL value, ecpglib will raise a run-time error.