MySQL：如何将表中的所有列插入到新表中，而对于不匹配的额外列如何插入NULL？

Question

Let me explain

• I have a MySQL table [Table A] with 89 Columns and 5 Million rows.
• I have to add 10 new columns (default NULL ) to [Table A]. Currently performing Alter Statement on [Table A] take more than 2 hours.

• I copied the DDL structure from [Table A] to [copied_Table A] as

  CREATE TABLE copied_table_a LIKE table_a;

• The I added 10 columns to copied_table_a .

• Now I want to insert all data from table_a to copied_table_a as

  mysql> INSERT copied_table_a SELECT * FROM table_a; ERROR 1136 (21S01): Column count doesn't match value count at row 1

Question
- What is the best way to get data now to copied_table_a ?

Answer 1

I suggest that you list all columns, but you can do:

INSERT INTO copied_table_a
    SELECT a.*,
           NULL, NULL, NULL, NULL, NULL,
           NULL, NULL, NULL, NULL, NULL
    FROM table_a; 

Answer 2

If you want a quick way to save typing you could make use of the information_schema.columns table :

select concat("insert into copied_table_a (",
               group_concat(column_name),
               ") select ",
               group_concat(column_name)," from ",table_name)
from information_schema.columns
where table_name = 'table_a';

To generate the SQL for you. Only really good for a one-off but quite fun to play around with.