Mysql – Duplicating a MySQL table, indices, and data

MySQL

How do I copy or clone or duplicate the data, structure,
and indices of a MySQL table to a new one?

This is what I've found so far.

This will copy the data and the structure,
but not the indices:

create table {new_table} select * from {old_table};

This will copy the structure and indices,
but not the data:

create table {new_table} like {old_table};

Best Answer

To copy with indexes and triggers do these 2 queries:

CREATE TABLE new_table LIKE old_table; 
INSERT INTO new_table SELECT * FROM old_table;

To copy just structure and data use this one:

CREATE TABLE new_table AS SELECT * FROM old_table;

I've asked this before:

Copy a MySQL table including indexes

Related Solutions

Mysql – concatenate multiple MySQL rows into one field

You can use GROUP_CONCAT:

SELECT person_id,
   GROUP_CONCAT(hobbies SEPARATOR ', ')
FROM peoples_hobbies
GROUP BY person_id;

As Ludwig stated in his comment, you can add the DISTINCT operator to avoid duplicates:

SELECT person_id,
   GROUP_CONCAT(DISTINCT hobbies SEPARATOR ', ')
FROM peoples_hobbies
GROUP BY person_id;

As Jan stated in their comment, you can also sort the values before imploding it using ORDER BY:

SELECT person_id, 
       GROUP_CONCAT(hobbies ORDER BY hobbies ASC SEPARATOR ', ')
FROM peoples_hobbies
GROUP BY person_id;

As Dag stated in his comment, there is a 1024 byte limit on the result. To solve this, run this query before your query:

SET group_concat_max_len = 2048;

Of course, you can change 2048 according to your needs. To calculate and assign the value:

SET group_concat_max_len = CAST(
                     (SELECT SUM(LENGTH(hobbies)) + COUNT(*) * LENGTH(', ')
                           FROM peoples_hobbies
                           GROUP BY person_id) AS UNSIGNED);

Mysql – Should I use the datetime or timestamp data type in MySQL

Timestamps in MySQL are generally used to track changes to records, and are often updated every time the record is changed. If you want to store a specific value you should use a datetime field.

If you meant that you want to decide between using a UNIX timestamp or a native MySQL datetime field, go with the native format. You can do calculations within MySQL that way ("SELECT DATE_ADD(my_datetime, INTERVAL 1 DAY)") and it is simple to change the format of the value to a UNIX timestamp ("SELECT UNIX_TIMESTAMP(my_datetime)") when you query the record if you want to operate on it with PHP.

Best Answer

Related Solutions

Mysql – concatenate multiple MySQL rows into one field

Mysql – Should I use the datetime or timestamp data type in MySQL

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