php mysql只更新空列

Consider I have 4 columns in a table and i have datas for 3 columns like below

考虑我在表中有4列,我有3列的数据,如下所示

TableTest

Col1  | Col2  | Col3
D11   | D12   |   
D21   | D22   |

Normally the update query would be

通常更新查询将是

Update TableTest SET Col1 = D11 , Col2 = D12 , COL3 = newdata Where Col1= D11

The Scenario is , the update query should only push data to the COL3 , it should skip the Col1 and Col2, as it has already filled with data(even if same or different data for the Col1 and Col2)

方案是,更新查询应该只将数据推送到COL3,它应该跳过Col1和Col2,因为它已经填充了数据(即使Col1和Col2的数据相同或不同)

5 个解决方案

#1

This might help -

这可能有所帮助 -

UPDATE TableTest a
INNER JOIN TableTest b ON a.Col1 = b.Col1
SET a.Col3 = 'newData'
WHERE a.Col3 IS NULL

An INNER JOIN with the same table so that it updates the appropriate row!

INNER JOIN具有相同的表,以便更新相应的行!

#2

If you just want to update COL3 than don't include other columns in UPDATE query.

如果您只想更新COL3而不是在UPDATE查询中包含其他列。

Query:

Update TableTest SET COL3 = newdata Where Col1= D11

#3

You should update whole table using single query as:

您应该使用单个查询更新整个表:

Update TableSet SET COL3=CONCAT('D',CONVERT(Substr(Col2,2),INT)+1)

This will update table as follows:

这将更新表如下:

TableTest

Col1  | Col2  | Col3
D11   | D12   |  D13 
D21   | D22   |  D23

#4

Just do it, like this:

就这样做,就像这样:

Update TableTest SET  COL3 = newdata Where Col1= D11

#5

In UPDATE query, there is no need to reassign the value of col1 and col2 if those values are not changing.

在UPDATE查询中,如果这些值没有更改,则无需重新分配col1和col2的值。

UPDATE TableTest 
SET COL3 = newdata 
WHERE Col1= 'D11';

#1