The key to using simple CASE statements effectively is understanding how to compare an expression to fixed values.The expression in a simple CASE statement can be a column name, a function, or any valid SQL expression. The values in the WHEN clauses are the fixed values against which we wan...
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'SELECT*,CASE...
2.举例: 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...
我想使用CASE语句根据某些条件选择输入的数据SQL中的CASE WHEN使用 Case具有两种格式。简单Case函数和Case搜...
PreparedStatement 是Java编程语言中的一个接口,用于执行预编译的SQL语句。它继承自 Statement 接口,允许在执行SQL查询之前将参数添加到SQL语句中。...此外,它允许参数化查询,即将动态值作为参数传递到SQL语句中,防止了SQL注入攻击的风险。...防止 SQL 注入攻击: 通过参数化查询,PreparedStatement 允许将参数传递到 SQL...
Simple Case Statement CASE [input_expression] WHEN when_expression THEN when_true_result_expression [...n] [ELSE else_result_expression] END Search Case Statement CASE WHEN Boolean_expression THEN when_true_result_expression [...n] [ELSE else_result_expression] END ...
SQL---CASE WHEN条件表达式(conditional statement) 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。)...
SQL USEAdventureWorks2022; GOSELECTProductNumber,Category=CASEProductLineWHEN'R'THEN'Road'WHEN'M'THEN'Mountain'WHEN'T'THEN'Touring'WHEN'S'THEN'Other sale items'ELSE'Not for sale'END,NameFROMProduction.ProductORDERBYProductNumber; GO B. Use a SELECT statement with a searched CASE expression ...
CASE selector WHEN selector_value_1 THEN statements_1 WHEN selector_value_1 THEN statement_2 ... ELSE else_statements END CASE; Code language: PostgreSQL SQL dialect and PL/pgSQL (pgsql) Let’s examine the syntax of the simple CASE statement in detail: 1) selector The selector is an...
如果在一開始的 Case 中找不到符合項目,Case Else 陳述式才會引導陳述式執行。在相同的 Select 區塊的 Case Else 之後,出現 Case 陳述式。錯誤ID:BC30321若要更正這個錯誤移動Case Else 至 Case 陳述式後的適當位置。請參閱參考Select...Case 陳述式 (Visual Basic)...