I need to copy the data of an old table with millions of rows to a newer table, with a slightly different definition. Most importantly, there is one new field with a null-default, and a varchar field became an enum (with directly mapping values).
Old table:
id : integer
type : varchar
New table:
id : integer
type : enum
number : integer, default null
All of the possible string values of type are within the new enumeration.
I tried the following:
insert into new.table select * from old.table
But I obviously get:
Insert value list does not match column list: 1136 Column count doesn't match value count at row 1
You can copy the table data and structure from phpmyadmin window, and then modify the new table and add the new column.
Using the INSERT ... SELECT syntax:
INSERT INTO new.table `id`, `type` SELECT `id`, `type` FROM old.table
Apparently the varchar to enum remapping isn't a problem.
Related
I need to change column type from tinyInt(used as bool) to Varchar, without loosing data.
I have found many answers on stack-overflow but all of them are written in postgres and I have no idea how to rewrite it in Mysql.
Answers for this problem on stack-overflow looks like that:
ALTER TABLE mytabe ALTER mycolumn TYPE VARCHAR(10) USING CASE WHEN mycolumn=0 THEN 'Something' ELSE 'TEST' END;
How would similar logic look like in Mysql?
The syntax you show has no equivalent in MySQL. There's no way to modify values during an ALTER TABLE. An ALTER TABLE in MySQL will only translate values using builtin type casting. That is, an integer will be translated to the string format of that integer value, just it would in a string expression.
For MySQL, here's what you have to do:
Add a new column:
ALTER TABLE mytable ADD COLUMN type2 VARCHAR(10);
Backfill that column:
UPDATE mytable SET type2 = CASE `type` WHEN 0 THEN 'Something' ELSE 'TEST' END;
If the table has millions of rows, you may have to do this in batches.
Drop the old column and optionally rename the new column to the name of the old one:
ALTER TABLE mytable DROP COLUMN `type`, RENAME COLUMN type2 to `type`;
Another approach would be to change the column, allowing integers to convert to the string format of the integer values. Then update the strings as you want.
ALTER TABLE mytable MODIFY COLUMN `type` VARCHAR(10);
UPDATE mytable SET `type` = CASE `type` WHEN '0' THEN 'Something' ELSE 'TEST' END;
Either way, be sure to test this first on another table before trying it on your real table.
Have some tables:
CREATE TABLE `asource` (
`id` int(10) unsigned NOT NULL DEFAULT '0'
);
CREATE TABLE `adestination` (
`id` int(10) unsigned NOT NULL DEFAULT '0',
`generated` tinyint(1) GENERATED ALWAYS AS (id = 2) STORED NOT NULL
);
I copy a row from asource to adestination:
INSERT INTO adestination
SELECT asource.*
FROM asource;
The above generates an error:
Error Code: 1136. Column count doesn't match value count at row 1
Ok, quite strange to require me to mention generated query. But ok, I add that column to the query:
INSERT INTO adestination
SELECT asource.*, NULL AS `generated`
FROM asource;
This has worked fine in 5.7.10. However, it generates an error in 5.7.11 (due to a fix:
Error Code: 3105. The value specified for generated column 'generated' in table 'adestination' is not allowed.
Ok, next try:
INSERT INTO adestination
SELECT asource.*, 1 AS `generated`
FROM asource;
But still the same error. I have tried 0, TRUE, FALSE but the error persists.
The DEFAULT value which is stated as the only allowed value (specs or docs). However, the following generates a syntax error (DEFAULT is not supported there):
INSERT INTO adestination
SELECT asource.*, DEFAULT AS `generated`
FROM asource;
So, how can I copy a row from one table to another using INSERT INTO ... SELECT if the destination table adds some columns where some of them are GENERATED?
The code calling this query is generic and has no knowledge what columns that particular tables have. It just knows which extra columns the destination table has. The source table is a live table, the destination table is a historical version of the source table. It has few columns extra like user id made the change, what type of the change it is (insert, update, delete) when etc.
Sadly this is just how MySQL works now to "conform to SQL standards".
The only value that the generated column can accept in an update, insert, etc. is DEFAULT, or the other option is to omit the column altogether.
My poor mans work around for these are to just disable the generated column while I'm working with the data (like for importing a dump) and then go back and add the generated column expression afterwards.
You must declare the columns
Insert into adestination (id, generated)
select id, 1
from asource;
It is best practice to list out the columns, and use null as field1 for the auto incremented id field.
INSERT INTO adestination
(id,
field1,
field2)
SELECT
null AS generated,
asource.field1,
asource.field2
FROM asource;
I have a table called teachers with a column ,"username", which is a VARCHAR(50). I'm trying to concatenate values in that column with a string, "#gmail.com", and insert the concatenated values into a temp table that has one column, "email", which is VARCHAR(100).
Using INSERT INTO temp SELECT CONCAT(username,'#gmail.com') FROM teachers;
The code runs but only inserts the VARCHAR(50) username, not the '#gmail.com'. This is what happens for all values except 2 in the whole table.
Need assistance on the following. How can I copy data from one SQL column table to another sql column table?
I have the following tables
dbo.Thecat62 and dbo.thecase6
inside dbo.Thecat62 , I need to copy the column Work_Order_Job_Start_Date values to dbo.thecase6 column Job_Start_Date. Currently there are null value in the Job_Start_Date column in dbo.thecase6.
I have tried using the following command
INSERT INTO dbo.thecase6 (Job_Start_Date)
SELECT Work_Order_Job_Start_Date
FROM dbo.thecat62
but received the error Cannot insert the value NULL into column 'CaseNo', table 'Therefore.dbo.TheCase6'; column does not allow nulls. INSERT fails.
The statement has been terminated.
Any help will be great!
Thanks!
Because on this table Therefore.dbo.TheCase6 for CaseNo you have specify Not NULL Constraints
something like this
CaseNo int NOT NULL
But you did not select the CaseNo column from the dbo.thecat62 table, so you are explicitly trying to insert nulls into a non-nullable column.
You just need to select the CaseNo column, as well, presuming it does not contain any nulls in teh source table.
INSERT INTO dbo.thecase6 (Job_Start_Date,CaseNo)
SELECT Work_Order_Job_Start_Date,CaseNo FROM dbo.thecat62
The error says it has a column CaseNo which doesn't allow NULL.
Cannot insert the value NULL into column 'CaseNo', table 'Therefore.dbo.TheCase6';
You are inserting rows in the new table which will have just 1 column filled and rest of the columns will be empty
Either
Alter the table in which you are inserting the data and allow the column to allow null values.
Or
if you don't want to allow null values, update the null values to some default values.
I am using MySQL database.
I have one table having column with datatype binary(16).
I need help with the insert statement for this table.
Example:
CREATE TABLE `assignedresource` (
`distid` binary(16) NOT NULL
)
insert into assignedresource values ('9fad5e9e-efdf-b449');
Error : Lookup Error - MySQL Database Error: Data too long for column 'distid' at row 1
How to resolve this issue?
You should remove the hyphens to make the value match the length of the field...
Example:
CREATE TABLE `assignedresource` (
`distid` binary(16) NOT NULL
)
insert into assignedresource values ('9fad5e9eefdfb449');
Also, MySQL standard is to use this notation to denote the string as binary... X'9fad5e9eefdfb449', i.e.
insert into assignedresource values (X'9fad5e9eefdfb449');
Well, assuming that you want to strictly insert a hexadecimal string, first you need to remove the dashes and then "unhex" your string before inserting it into a binary(16) data type column, the code would go like this:
INSERT INTO `assignedresource` VALUES(UNHEX(REPLACE('9fad5e9e-efdf-b449','-','')));
Also... the "usable" data you are inserting is actually 8 bytes after undashing it, so binary(8) would do fine if you plan on not storing the dashes.
You can strip the hyphens and perpend 0x to the value unquoted, like this:
insert into assignedresource values (0x9fad5e9eefdfb449);
As well as, as this (mentioned in other answers):
insert into assignedresource values (X'9fad5e9eefdfb449');
Both are valid notation for a hexadecimal literal.
Your string is 18 char long, change the database
CREATE TABLE `assignedresource` (
`distid` binary(18) NOT NULL
)