2. 搜索式CASE语句 搜索式CASE语句有个能够产生boolean(true,false,null)的搜索条件,当特定搜索条件计算结果为TRUE时,会执行与该条件相关的语句组合。搜索式CASE语句的语法如下所示: CASE WHEN SEARCH CONDIDTION 1 THEN STATEMENT 1; WHEN SEARCH CONDIDTION2 THEN STATEMENT 2; ... WHEN SEARCH CONDIDTIONN T...
SQL>show userUSER为"HR"SQL>SELECTfirst_name,last_name,department_id,2CASEdepartment_id3WHEN10THEN'Accounting'4WHEN20THEN'Sales'5WHEN30THEN'Finance'6ELSE'Other'7ENDdepartment_name8FROMemployees where rownum<2;FIRST_NAMELAST_NAMEDEPARTMENT_IDDEPARTMENT_NAME---Steven King90OtherSQL> ※测试使用的Orac...
12 rows selected 与case when 配合: select case when grouping(e.department_id)=0 then ''||e.department_id else 'All Departments' end as department_id , case when grouping(e.job_id)=0 then e.job_id else 'All Jobs' end as job_id, avg(e.salary) from hr.employees e where e.depart...
在Oracle SQL中,CASE表达式是一种条件表达式,用于根据不同的条件返回不同的结果。它可以在SELECT语句、WHERE子句、ORDER BY子句和其他SQL语句中使用。 CASE表达式有两种形式:简单CASE表达式和搜索CASE表达式。 简单CASE表达式: 简单CASE表达式使用固定的值进行比较,并根据每个值返回不同的结果。它的语法如下: ...
There’s noifkeyword in SQL. If you want to doif-else-thenlogic inselect,whereor anywhere else in a statement, you need acaseexpression. This is a series ofwhenclauses that thedatabaseruns in order: For example, if you want to map exam correct percentages to grade letters according to...
SELECT*FROMlocationsWHEREcountry_idin('US','CA','UK')ORDERBYcountry_id,CASEcountry_idWHEN'US'THENstateELSEcityEND;Code language:SQL (Structured Query Language)(sql) In this example, the result set is sorted by the column state when the country is theUSand by the column city for all othe...
Simple PL/SQL CASE statement A simple CASE statement evaluates a single expression and compares the result with some values. The simple CASE statement has the following structure: CASE selector WHEN selector_value_1 THEN statements_1 WHEN selector_value_1 THEN statement_2 ... ELSE else_state...
CASE表达式可以再SQL中实现if-then-else型的逻辑,9i及以上版本支持CASE表达式。 1. 使用简单CASE表达式 语法如下: CASE search_expression WHENexpression1 THEN result1 … ELSEdefault_result END store@PDB1> select product_id,product_type_id,caseproduct_type_id ...
SQL 执行报错 ORA-00979: 'SYS.A.NUM2' not a GROUP BY expression,示例如下。 obclient> select a.num1,decode(a.num2,0,decode(a.num3,(-1),2,0),a.num2) cc from test a group by num1 ,decode(a.num2,0,decode(a.num3,(-1),2,0),a.num2) order by decode(a.num2,0,decode(...
SELECT CASE WHEN dummy = 'x' THEN '-' ELSE 3 END FROM dual 1. 2. 3. 4. 5. 6. 上面SQL会报下面错误: ORA-00932: 数据类型不一致: 应为 CHAR, 但却获得 NUMBER 这是因为 THEN 后面是 CHAR 类型数据,而 ELSE 后面是 NUMBER 类型数据,数据类型不一致报错。