如何自学SQL？ - 知乎
sql不能像编程语言一样，使用变量、条件逻辑、循环结构等对过程进行定义，以获得想要的结果。sql直来直去，只要定义必要的输入输出，没有对过程的控制。 了解sql的大致情况后，我们再 …
Should I use != or <> for not equal in T-SQL? - Stack Overflow
Mar 26, 2018 · Yes; Microsoft themselves recommend using <> over != specifically for ANSI compliance, e.g. in Microsoft Press training kit for 70-461 exam, "Querying Microsoft SQL …
SQL WITH clause example - Stack Overflow
Sep 23, 2012 · The SQL WITH clause was introduced by Oracle in the Oracle 9i release 2 database. The SQL WITH clause allows you to give a sub-query block a name (a process also …
sql是什么，通俗的说，太专业听不懂？ - 知乎
sql是一门语言，就和我们平时说话一样，有主谓宾的层次结构，同样sql也有自己的一套语法规则。 记住这些语法规则就可以与数据库打交道了，不管是查询，新增，更新，删除数据，都可 …
How do I perform an IF...THEN in an SQL SELECT?
Sep 15, 2008 · The CASE expression cannot be used to control the flow of execution of Transact-SQL statements, statement blocks, user-defined functions, and stored procedures. If your …
如何学习 SQL 语言？ - 知乎
SQL 真的不难，用 20 个小时来学习完全足够了。 「1」刷题前之前了解下 SQL 是什么： 结构化查询语言(Structured Query Language)简称SQL，是一种数据库查询和程序设计语言，用于存 …
sql - Find records from one table which don't exist in another
If you look at the query plan it will look something like this and you can confirm your new index is actually being used. Note this is for SQL Server but should be similar for MySQL. With the …
SQL- Ignore case while searching for a string - Stack Overflow
Apr 18, 2013 · I have the following data in a Table PriceOrderShipped PriceOrderShippedInbound PriceOrderShippedOutbound In SQL I need to write a query which searches for a string in a …
t sql - How to format datetime in SQL SERVER - Stack Overflow
In SQL Server 2012 and up you can use FORMAT():. SELECT FORMAT(CURRENT_TIMESTAMP, 'yyyy-MM-dd hh:mm:ss tt') In prior versions, you might …
database - How to select unique records by SQL - Stack Overflow
When I perform SELECT * FROM table I got results like below: 1 item1 data1 2 item1 data2 3 item2 data3 4 item3 data4 As you can see, there are dup records from column2 (item1 are …