When modifying a record in MySQL, the update operation field = field + string

In some scenarios, we need to modify our varchar type fields, and the result of the modification is the concatenation of two fields or the concatenation of a field + a string.

As shown below, we want to modify the name in the xx_role table to name+id.

In MySQL, if we operate directly through "+", an error will be prompted.

The operator "+" is used to add numbers. Here, the keyword concat is needed to indicate concatenation.

Similarly, we can also use field + string to concatenate.

Here we will briefly talk about the "+" operation, which is used to add numeric fields, as shown below:

Supplement: Use update in mysql to update multiple fields at the same time, including select query

Wrong attempts:

update table name set (field 1, field 2, field 3, ...) = (select value 1, value 2, value 3, ...) where condition

Correct way:

# UPDATE OldData o, NewData n without using select 
SET o.name = n.name, o.address = n.address 
where n.nid=234 and o.id=123;

# Using select situation UPDATE OldData o, (select name, address from NewData where id = 123) n 
SET o.name = n.name, o.address = n.address 
where n.nid=234;

The above is my personal experience. I hope it can give you a reference. I also hope that you will support 123WORDPRESS.COM. If there are any mistakes or incomplete considerations, please feel free to correct me.