What does double bars (||) mean in SQL? - Stack Overflow
@Martin: I know, but the DBMS is relevant quite often; it's a good habit to get into. SQL Server uses '+' as a string concatenation operator, for instance. (Of course, the better solution would …
What does <> (angle brackets) mean in MS-SQL Server?
2013年11月8日 · <> operator means not equal to in MS SQL. It compares two expressions (a comparison operator). When you compare nonnull expressions, the result is TRUE if the left …
如何自学SQL？ - 知乎
了解SQL的大致情况后，我们再来看看如何学？ SQL是所有数据库查询的语言，sql由于本身结构化的特点，非常容易入手。针对不同的数据库，如hivesql、mysql、sqlserver、oracle等，sql …
sql - Not equal <> != operator on NULL - Stack Overflow
2014年10月9日 · <> is Standard SQL-92; != is its equivalent. Both evaluate for values, which NULL is not -- NULL is a placeholder to say there is the absence of a value. Which is why you …
What does the "@" symbol do in SQL? - Stack Overflow
2012年7月30日 · The @CustID means it's a parameter that you will supply a value for later in your code. This is the best way of protecting against SQL injection. Create your query using …
What does SQL Select symbol - mean? - Stack Overflow
2014年4月29日 · sql server: + (infix operator), concat ( vararg function ) Edit: Now Azure SQL also supports ANSI SQL ...
Should I use != or <> for not equal in T-SQL? - Stack Overflow
2009年4月6日 · 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 - Equals (=) vs. LIKE - Stack Overflow
2009年2月12日 · Using "=" is a tiny bit faster in this case (searching for an exact match) - you can check this yourself by having the same query twice in SQL Server Management Studio, once …
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 …
SQL Greater than, Equal to AND Less Than - Stack Overflow
2012年3月7日 · I want to create a query like the following, But im unsure of how to code it correctly, I want it to return all bookings within 1 hour of a StartTime, Here is what i came up …