Database SQL string connection function: cancat ()

From: http://blog.sina.com.cn/s/blog_4b93170a0100biyp.html

Sometimes, we need to link the data obtained from different columns. Each database provides methods to achieve this purpose:

• MySQL: Concat ()
• ORACLE: Concat (), |
• DB2: Concat (), |
• SQL Server: +

The Concat () syntax of MySQL is as follows:

Concat (string 1, string 2, string 3 ,...):Concatenates string 1, string 2, and string 3.

Note:: Concat () of Oracle and DB2 only allows two parameters. In other words, only two strings can be connected at a time.

Syntax: Concat (arg1, arg2)
The Concat function returns the connection between two strings.
Eg: Select Concat (first_name, last_name) from T1

However, in Oracle and DB2, we can use '|' to concatenate multiple strings at a time.

Let's look at several examples. Suppose we have the following table:

Geography table

Region_name	Store_name
East	Boston
East	New York
West	Los Angeles
West	San Diego

Example 1:

MySQL/Oracle:
Select Concat (region_name, store_name) from geography
Where store_name = 'boston ';

Result:

'Astboston'

Example 2:

Oracle:
Select region_name | ''| store_name from geography
Where store_name = 'boston ';

Result:

'East Boston'

Example 3:

SQL Server:
Select region_name + ''+ store_name from geography
Where store_name = 'boston ';

Result:

'East Boston'