SQL adds two columns of int data from the same table, and some of the data is empty

Source: Internet
Author: User

You can't add that!

Some data is null, null+ any value =null

Not if you say that.

Update Set HY_MYGGCYSWCQKB. Sj_by_sr=hy_myggcyswcqkb. Sj_by_sr+hy_myggcyswcqkb. Sj_by_sr_tz-hy_myggcyswcqkb. SJ_BY_SR_TJ;

If there is a column that is not NULL, the result of the addition is null.

Normal, yes.

SELECT
Total + Money
From
Table

You can do it.
But:
Some of the data is empty and needs to be based on different databases, with unused functions
That is, if the data is empty, then it is calculated according to 0
Oracle or DB2 using NVL (total, 0) + NVL (Money, 0)
SQL Server uses ISNULL (total, 0) + ISNULL (Money, 0)
MySQL or SQLite use Ifnull (total, 0) + ifnull (Money, 0)

SQL adds two columns of int data from the same table, and some of the data is empty

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