Character columns of SQL Max

SQL Max can be used to calculate numeric or character columns.

 

However, you must pay attention to the special case of Max character columns.

For example, if the key column is a character column, there are currently 1, 2, 3, 4, 5... 9 Data

Now add 1 to the front to get the next key value.

 

The general method is as follows:

Declare @ next_key int
Select @ next_key = max (customsort) from persons

Print @ next_key + 1

 

The above code always returns 10, resulting in no auto-increment of next_key.

 

Declare @ next_key int

Select @ next_key = max (cast (customsort as INT) from persons

Print @ next_key + 1

 

The preceding method converts customsort to int to automatically increase the key.