difference between null and blank

The difference between Null and NULL String ''in Oracle: Q: What is Null? A: When we do not know the specific data, it is also unknown. We can use NULL. We call it NULL. in ORACLE, the column length containing NULL values is zero. ORACLE allows

Difference between NULL and MySQL NULL strings bitsCN.com Difference between NULL and MySQL NULL strings We often see MySQL NULL strings and NULL values, but they are not a concept. The following describes the differences between NULL and MySQL

Null is not an object, ' is an objectFrom ', you can know that this is a string type of data and is a zero-length string.From NULL, you can only know that there is no value assigned, is empty, he does not belong to any data type.In the actual use of

DBNull class Indicates a value that does not exist. This class cannot be inherited. Namespace: System Assembly: mscorlib (in mscorlib. dll) The DBNull class indicates a non-existent value. For example, in a database table, a column in a row may not

the difference between String.empty,null and ""String. Empty is equivalent to ""Typically used for initialization of stringsLike what:String A;Console.WriteLine (a);//error here, because there is no initialization of aAnd the following will not

DBNull class Represents a value that does not exist. This class cannot be inherited. Namespaces: System Assembly: mscorlib (in mscorlib.dll) The DBNull class represents a value that does not exist. For example, in a table in a database, a column

The DBNull class indicates a value that does not exist. This class cannot be inherited. Namespace: System Assembly: mscorlib (in mscorlib. dll) DBNull class indicates a non-existent value. For example, in a database table, a column in a row may not

The empty keyword is used to indicate the value of an uninitialized variable, unlike null Null keyword is used to indicate that the variable contains data that is not valid, unlike empty Instance: Dim p Now IsEmpty (p) is true IsNull (p) is null For

What is the difference between echo and/dev/null in command for clearing file content? We know that there are many methods to clear the file content. This article only talks about the differences between echo "And/dev/null. 1. What is the black

1 isnotempty (str) equivalent to str! = NULL && str.length > Isnotblank (str) equivalent to str! = NULL && str.length > 0 && Str.trim (). length > 03 similarly 4 isEmpty equivalent to str = = NULL | | Str.length = = IsBlank equivalent to str = =