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To check if variable is null or empty use this: IF LEN(ISNULL(@var, '')) = 0 -- Is empty or NULL ELSE -- Is not empty and is not NULL
A null is neither an empty string (for character or datetime data types) nor a zero value (for numeric data types). The ANSI SQL-92 specification states that a null must be the same for all data types, so that all nulls are handled consistently. The System.Data.SqlTypes namespace provides null semantics by implementing the INullable interface.
The following example examines three strings and determines whether each string has a value, is an empty string, or is null. C#. Copy. Run. string s1 = "abcd"; string s2 = ""; string s3 = null; Console.WriteLine("String s1 {0}.", Test(s1)); Console.WriteLine("String s2 {0}.", Test(s2));
Since .NET 2.0 you can use: // Indicates whether the specified string is null or an Empty string. string.IsNullOrEmpty(string value); Additionally, since .NET 4.0 there's a new method that goes a bit farther: // Indicates whether a specified string is null, empty, or consists only of white-space characters.
4 sty 2011 · NULL means absence of value (i.e. there is no value), while empty string means there is a string value of zero length. For example, say you have a table to store a person' data and it contains a Gender column.
9 lut 2009 · Handling the Issue of NULL and Empty Values. Then let’s try to handle the record having the NULL value and set as a new value the string “NewValue” for the result set of our select statement. SQL Server provides 2 functions for doing this; (i) the ISNULL; and (ii) the COALESCE.
28 sty 2021 · SQL databases operate on 3-valued logic (true, false, null) when performing comparisons, as opposed to the boolean logic of C#. When translating LINQ queries to SQL, EF Core tries to compensate for the difference by introducing additional null checks for some elements of the query.
