sql case statement
SELECTOrderID, Quantity,CASEWHENQuantity>30THEN'The quantity is greater than 30'WHENQuantity=30THEN'The quantity is 30'ELSE'The quantity is under 30'ENDASQuantityTextFROMOrderDetails; SELECTCustomerName, City, CountryFROMCustomersORDERBY(CASEWHENCityISNULLTHENCountryELSECityEND); 以上例子等摘自:https...
Performance optimization: by reducing the complexity of the SQL queries, the CASE statement can also contribute to optimizing the performance and minimize the execution time, especially when it avoids the need for additional computations and transformations. ...
3. Calculating average with CASE WHEN CASE WHEN is like an IF statement in a programming language. It is useful when we need to calculate a statistic on a certain subset of the data. In the image above, I calculate an average price for products sold in the US. I wasn’t careful with...
CASE表达式是用来判断条件的,条件成立时返回某个值,条件不成立时返回另一个值。 语法: CASEWHENComparsionConditionTHENresultWHENComparsionConditionTHENresultELSEotherEND (注:各分支返回的数据类型需一致。) (注:when子句一定要有排他性,因为当when子句为真时,剩余的when子句会被忽略。) ...
SQL - CASETable of content The SQL CASE Statement CASE Statement with ORDER BY Clause CASE Statement with GROUP BY Clause CASE Statement with WHERE Clause CASE Statement with UPDATE CASE Statement with INSERT Previous Quiz Next The SQL CASE Statement...
SQL CASE The SQLCASEstatement evaluates a list of conditions and adds a column with values based on the condition. For example, -- add a new column 'order_volume' in the Orders table-- and flag any order greater than 10000 as 'Large Order'-- and smaller than 10000 as 'Small Order'...
PL/SQL also has CASE expression which is similar to the CASE statement. A CASE expression evaluates a list of conditions and returns one of multiple possible result expressions. The result of a CASE expression is a single value whereas the result of a CASE statement is the execution of a se...
CASE 语句有两种形式:简单 CASE 语句和搜索型 CASE 语句。 简单CASE 语句 (PL/SQL) 简单CASE 语句尝试将表达式 (称为选择器) 与一个或多个 WHEN 子句中指定的另一个表达式匹配。 发生匹配将导致执行一条或多条相应的语句。 已搜索的 CASE 语句 (PL/SQL) ...
CASE @Gender WHEN 0 THEN 'M' WHEN 1 THEN 'F' end, @Statecode, @salary) In the following screenshot, we can see the newly inserted row contains Gender M instead of value 0. Case Statement limitations We cannot control the execution flow of stored procedures, functions using a Case st...