在SQL中执行语句后，所有数据都为NULL

Question

Statement I used:

INSERT INTO table (addr2, addr3) 
    SELECT City, State 
    FROM table

I tried to reverse, but I don't know how.

I want to get my data back. All columns and fields are now null .

Answer 1

You said:

... basically just copying all the data from city and state and placing the data into the addr2 and addr3.fields

If you want to replace all existing addr2 with city and addr3 with state in all rows of the table, you want UPDATE , not INSERT :

UPDATE foo SET addr2 = city, addr3 = state;

... where foo is the name of the table.

Note, that will replace any values you previously had for addr2 and addr3 , so use this carefully. If you only want to replace addr2 and addr3 where they are NULL , you can do:

UPDATE foo SET addr2 = city WHERE addr2 IS NULL;
UPDATE foo SET addr3 = state WHERE addr3 IS NULL;

Or, perhaps:

UPDATE foo SET addr2 = city, addr3 = state WHERE addr2 IS NULL AND addr3 IS NULL;
UPDATE foo SET addr3 = CONCAT(city, ', ', state) WHERE addr2 IS NOT NULL AND addr3 IS NULL;

Or, depending upon what SQL engine you're using, you can also use ISNULL() :

UPDATE foo SET addr2 = ISNULL(addr2, city), addr3 = ISNULL(addr3, state);

So, delete the rows that you just inserted and then UPDATE the remaining rows as appropriate. You may want to backup your data first, just to be safe.