importpsycopg2importpandasaspdfromsqlalchemyimportcreate_engine,text# 连接数据库取数engine=create_engine...
In the order specified, evaluates input_expression = when_expression for each WHEN clause. Returns theresult_expressionof the firstinput_expression=when_expressionthat evaluates to TRUE. If noinput_expression=when_expressionevaluates to TRUE, the SQL Server Database Engine returns theelse_result_expres...
Since we cannot re-use aliases in T-SQL, we need to use the same expression inside the COUNT aggregate and in the GROUP BY clause. We can however use aliases in the ORDER BY clause, as demonstrated by using theStaffCountalias to sort the data on. If we would like to filter the data...
The case statement in SQL returns a value on a specified condition. We can use a Case statement in select queries along with Where, Order By, and Group By clause. It can be used in the Insert statement as well. In this article, we would explore the CASE statement and its various use...
If you want a full demonstration on how to work with the CASE statement in SQL, check the following tutorial on the provided link: https://linuxhint.com/sql-case-statement/ This tutorial mainly focuses on building a nested case statement in conjunction with the WHEN clauses. ...
-- CASE condition with ELSE clause in SQLSELECTcustomer_id, first_name,CASEWHENcountry ='USA'THEN'United States of America'WHENcountry ='UK'THEN'United Kingdom'ELSE'Unknown Country'ENDAScountry_nameFROMCustomers; Run Code Here, the result set contains a new column,country_namealong withcustomer...
SQL-GROUP BY语句在MySQL中的一个错误使用被兼容的情况 dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by ?...而DOS却是严格按照SQL的语法来的。...SQL的grop by 语法为, select 选取分组中的列+聚合函数 from 表名称 group by 分组的列 从语法格...
MySQL 数据库使用SQL SELECT语句来查询数据。 你可以通过 mysql> 命令提示窗口中在数据库中查询数据,或者通过PHP脚本来查询数据。...语法 以下为在MySQL数据库中查询数据通用的 SELECT 语法: SELECT column_name,column_name FROM table_name [WHERE Clause] [LIMIT...SELECT 命令可以读取一条或者多条记录。 你可...
Ignoring the case in awhereclause is very simple. You can, for example, convert both sides of the comparison to all caps notation: SELECT first_name, last_name, phone_number FROM employees WHEREUPPER(last_name) = UPPER('winand')
'WHEN MATCHED' cannot appear more than once in a 'UPDATE' clause of a MERGE statement. "EXECUTE AT" with Dynamic Linked Server Name "explicit value must be specified for identity column in table" error in SQL 2000 "FROM clause have the same exposed names. Use correlation names to distingui...