Back in the evening, the classmate said the interview encountered a SQL interview topic, did a bit of their own, summary summary.The topics are as follows: The following is a product data sheet (Product ID, color col, num), each of which is
PL/SQL script language value assignment statement syntax table and record comply with the type usage, select the statement if else usage anonymous block (1), assign value statement syntax PL/SQL values use: = "=" some rules need to be observed in
Case has two formats. Simple case function and case search function.--Simple Case functionCase SexWhen ' 1 ' Then ' men 'When ' 2 ' then ' women 'Else ' other ' END--case search functioncase If sex = ' 1 ' Then ' man 'When sex = ' 2 ' Then ' women
Case has two formats. Simple case function and case search function.--Simple Case functionCase SexWhen ' 1 ' Then ' men 'When ' 2 ' then ' women 'Else ' other ' END--case search functioncase If sex = ' 1 ' Then ' man 'When sex = ' 2 ' Then ' women
Case has two formats. Simple case function and case search function.--Simple case function when ' 1 ' then ' Male ' when ' 2 ' then ' women ' else ' other ' end--case search function case when sex = ' 1 ' Then ' man ' when
Case has two formats. Simple case function and case search function.--Simple case function when ' 1 ' then ' Male ' when ' 2 ' then ' women ' else ' other ' end--case search function case when sex = ' 1 ' Then ' man ' when
--Simple case function when ' 1 ' then ' Male ' when ' 2 ' then ' women ' else ' other ' end--case search function case when sex = ' 1 ' Then ' man ' when Sex = ' 2 ' Then ' women ' else ' other ' ENDIn both of these ways,
SQL statement case when then else end returns a qualified value, sqlcase
Case has two formats
Simple Case functions and Case search functions:
-- Simple Case function CASE sex WHEN '1' then' male 'when' 2' then' female 'else' other 'ends -- Case
CASE has two formats:The simple CASE function compares an expression with a group of simple expressions to determine the result.The CASE search function calculates a group of Boolean expressions to determine the result.Both formats support the
Use of case, simple case functionA simple case expression that uses an expression to determine the return value.
Grammar:
Case Search_expression
When Expression1 THEN RESULT1
When Expression2 THEN result2
...
When Expressionn THEN Resultn
ELSE
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