计算字段 / 字段连接
MS SQL, Access
Oracle, PostgreSQL, SQLite, Firebird
MySQL
SELECT
Code +
' - '
+ Name
FROM
country
Code + ' - ' + Name
ABW - Aruba
AFG - Afghanistan
AGO - Angola
AIA - Anguilla
ALB - Albania
AND
- Andorra
ANT - Netherlands Antilles
ARE - United Arab Emirates
ARG - Argentina
...
拼接 把几个值首尾相接，合成一个较长的值。