Understand how SQL NULLIF compares two values and returns NULL if they are equal. Learn syntax and examples for using NULLIF in SQL queries.
Null Value Compare SQL> SQL> select * from dual where null=null; no rows selected SQL> --- SQL> select * from dual where null <> null; no rows selected SQL> --- SQL> select * from dual where null is null; D - X SQL> Related examples in the same category 1.= NULL or is N...
(nRow);// Add null values.nRow = table.NewRow(); nRow["ID"] = SqlInt32.Null; nRow["Description"] = SqlString.Null; table.Rows.Add(nRow);// Initialize variables to use when// extracting the data.SqlBoolean isColumnNull =false; SqlInt32 idValue = SqlInt32.Zero; SqlString ...
name)values(1,null);1rowcreated.SQL>insertintotest(id, name)values(2,'');1rowcreated.SQL>insertintotest(id, name)values(3,' ');--符号中' '有一个空格1rowcreated.SQL>insertintotest(id, name)values(4,' ');--符号中' '有两个空格1rowcreated.SQL>commit;Commitcomplete.SQL>select*...
StringCompareOptions 此选项不适用于列 Null 比率配置文件。 常规选项 RequestID 键入一个标识此配置文件请求的描述性名称。 通常无需更改自动生成的值。 另请参阅 数据事件探查任务编辑器(常规页) 单个表快速配置文件窗体(数据事件探查任务) 反馈 此页面是否有帮助?
你可以在字段名后面加上*N (new),*O (old),或*C (compare)来指定如何处理插入、更新或删除的字段数据值,如下所示: {fieldname*N} 对于UPDATE,在进行指定更改后返回新的字段值。 对于INSERT,返回插入的值。 对于DELETE,返回删除前的字段值。 {fieldname*O} ...
Nullable<int> i =null; Nullable<int> j =null;if(i == j) {// This branch is executed.} SQL -- Assume col1 and col2 are integer columns with null values.-- Assume that ANSI null behavior has not been explicitly-- turned off.Select…From…Wherecol1 = col2-- Evaluates to null, ...
That’s why SQL has the is null predicate to test whether a value is null or not and the is not distinct from predicate to compare two values while treating two null values as the same. Logical Operations Involving Unknown In logical connections (and, or), unknown behaves like the null ...
For higher values, the corresponding surrogate is returned. A value higher than 0xFFFF returns NULL instead of the corresponding surrogate. UNICODE Returns a UTF-16 code point in the range 0 - 0x10FFFF. Returns a UCS-2 code point in the range 0 - 0xFFFF. Match One Character WildcardWild...
SQL> insert into test(id, name) values(3, ' '); --符号中' '有一个空格 1 row created. SQL> insert into test(id, name) values(4, ' '); --符号中' '有两个空格 1 row created. SQL> commit; Commit complete. SQL> select * from test where name is null; ...