|Title:||cannot detect null or empty in field with parameterized query|
|Last Modified:||2018-04-26 16:40:36|
|Version Found In:||3.22|
anonymous added on 2018-03-25 12:58:24:
Hello, Here are is how the fields are defined: " PersId INTEGER PRIMARY KEY UNIQUE NOT NULL, " + " MiddleName NCHAR (50) DEFAULT NULL," + " BirthDate TEXT NULL DEFAULT ''," + " Gender NCHAR (1) NULL," + I inserted rows with NULL in the NCHAR and TEXT fields. Then, searching for NULL values in these fields did no return anything. Example query: "SELECT * FROM tblPerson WHERE MiddleName = @MiddleName " Example setting parameter: oDataAdapter.SelectCommand.Parameters.AddWithValue(("@MiddleName"), DBNull.Value) Note that this issue manifests only with parameterized queries. Thank you. Florin
mistachkin added on 2018-03-26 18:24:00:
Checking for equality with NULL in SQL may not produce the desired results. In general, expressions that have one or more NULL operands will produce a NULL result. The SQL query in this ticket should probably be revised to use the IS NULL check with an OR operator in order to find the matching rows.