在SQL语言中,WHERE子句用于筛选满足特定条件的数据行。它可以与SELECT语句一起使用,以便从数据库表中检索特定的数据。 WHERE子句中的SELECT条件是指在WHERE子句中使用的条件表达式,用于指定所需的数据行。条件表达式可以使用比较运算符(如等于、不等于、大于、小于等)、逻辑运算符(如AND、OR、NOT)和通配符(如LIKE)来...
WHERE 子句指定搜尋條件,以識別您要擷取、更新或刪除的一或多個列。 然後,您使用 SQL 陳述式處理的列數取決於滿足 WHERE 子句搜尋條件的列數。 搜尋條件由一或多個述詞組成。 述詞指定您要 SQL 套用至表格的一或多個指定列的測試。 在下列範例中, WORKDEPT = 'C01' 是述詞, WORKDEPT 和 'C01' 是表示...
MySQL的WHERE子句用于过滤记录,只返回满足指定条件的记录。它是SQL查询语句中的一个重要部分,用于指定从表中检索哪些行。 相关优势 灵活性:可以根据不同的条件进行查询,非常灵活。 效率:通过使用索引,可以显著提高查询效率。 精确性:可以精确地获取所需的数据,减少不必要的数据传输。
First-CASE是一个表达式（不是语句）。它按顺序工作，第一个WHEN条件为True时将返回THEN***值和EXIT*...
This example uses the WHERE clause to define multiple conditions, but instead of using theAND condition, it uses theOR condition. In this case, this SQL statement would return all records from theproductstable where theproduct_nameis either PearorApple. ...
问题是我必须根据多个条件得到一行,匹配的越多,就决定了最终的匹配。如果上面的语句与bottom或statement匹配,则返回一行,但是如果它与first或statement匹配,则返回两个语句的结果。 限制1也不起作用,因为有时它会优先考虑错误的结果。 EDIT: 因为表的方式是两行都是真的,我的理解是SQL取第一个为真的并返回它。
The basic syntax of the SQL WHERE clause is as shown below − DML_Statement column1,column2,...columnNFROMtable_nameWHERE[condition]; Here, the DML_Statement can be any statement, such as SELECT, UPDATE, DELETE etc. You can specify a condition using thecomparison or logical operatorssuch...
I was searching for a good replacement for the case statement in where condition. I got it... Thank you very much for posting this logic... Thanks Nishad Stelban 2007-07-11re: WHERE clause logic Jeff, thank you; this was extremely helpful! I have a SQL Reporting Services report which...
ExampleGet your own SQL ServerSelect all customers from Mexico:SELECT * FROM Customers WHERE Country='Mexico'; Try it Yourself » SyntaxSELECT column1, column2, ... FROM table_name WHERE condition; Note: The WHERE clause is not only used in SELECT statements, it is also used in UPDATE,...
This Oracle WHERE clause example uses the WHERE clause to define multiple conditions. In this case, this SELECT statement uses the AND condition to return all suppliers that are located in the state of California and whose supplier_id is less than or equal to 750.Example...