从sqlite的不同表中将数据从一列复制到另一列

Question

I want to copy data to column A in Table1 from column B in Table2. Rows for column A are empty and there are exists other columns in Table1 with already populated data. So I need to grab the whole column B from Table2 and insert all those values in column A in Table1. The two table are completely identical, except that column A has no values at all.

How do I do this in sqlite3?

Answer 1

Use:

INSERT INTO TABLE1
SELECT B,
       NULL,
       NULL,
       NULL
  FROM TABLE2

Use NULL as the placeholder for however many columns you can't populate from TABLE2, assuming TABLE1 columns allow NULL values.

Answer 2

尝试以下操作：插入表1（A）从表2选择B

Answer 3

UPDATE TABLE1 SET A = (SELECT B FROM TABLE2 WHERE ...)

Come to think of it, if the tables are truly identical, why do you need two of them? In any case you can also do this:

BEGIN;
DELETE FROM TABLE1;
INSERT INTO TABLE1 (A, col1, col2, ...) SELECT (B, col2, col2, ...) FROM TABLE2;
COMMIT;