I'm currently trying to find a way to separate the mysql export function (using phpmyadmin and/or shell)
Following situation:
I have two databases which were the same at some state but over time only one got updated. So for example:
- database1 has table "users" with columns "UID" and "username"
- database2 has table "users" with columns "UID" "username" and "status"
Now i want to export database2 and import it to database1. database2 contains data I DONT need anymore. But database1 contains important data. So I need something that gives me the possibility to somehow "merge" these databases without data loss on database1 and without merging data from database2.
The merge should look if the table exists, if not -> create it
The merge should look if the columns exist in the table, if not -> create it
What I have tried so far:
I've first tried it with the inbuilt PHPmyadmin export function (advanced options). This would give me the following result:
CREATE TABLE IF NOT EXISTS `users` (
`UID` int(11) NOT NULL,
`username` varchar(25) NOT NULL,
`status` int(2) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1;
When I import this, of course, nothing special will happen since the table already exists and so the 'status' column does not get created.
On my research I found a possibility to export a database separated from table creation using shell using the command (blacked out database name and user/pass):
mysqldump -t --insert-ignore --skip-opt -u USER -p PASSWORD -h 127.0.0.1 database > database.sql
But this gives me an insert option with data (which I dont need)
INSERT IGNORE INTO `users` VALUES (1,"bla",1);
Is there any different possibility?
Sure I know I could write it by hand to alter the columns into the table but it sure has to be automatic since its not only the table I named in the example.
To be 100% clear what I'm trying to achieve, a pseudo handwritten sql script:
CREATE TABLE IF NOT EXISTS 'users';
For every column -> IF NOT EXISTS column in 'users' -> ALTER TABLE 'users' ADD column def;
You can use MySQLWorkBench as well. Look video instruction
Related
I need to create a table with a file or anything, everything needs to be done as a sql script.
Can someone help me create a table without a csv file,
The name of the table is "videos"
The rows will be:
unique id
title
minutes
URL
When creating table to database via script you need to create a file where you will define structure of table with DDL (Data definition language).
For example
Create file table.sql. Open file and use CREATE TABLE statement for table creation.
CREATE TABLE videos(
id INT NOT NULL AUTO_INCREMENT,
minutes INT NOT NULL,
title VARCHAR(255) NOT NULL,
url VARCHAR(255) NOT NULL,
PRIMARY KEY ( id )
);
Afterwards you can run this script in many different ways. For example in Linux based operating systems you can run script with command mysql in form mysql -u user -p database_name < table.sql, where user is your username and database_name is name of database for which you want to create table.
I'm trying to create a data warehouse.
Is it possible to populate a table in db1, from data in db2.
For example
Corporate Database Table Route
CREATE TABLE ROUTE (
RouteID INTEGER(4) PRIMARY KEY,
RouteName VARCHAR (50) NOT NULL,
BoardingStop VARCHAR (50) NOT NULL,
AlightingStop VARCHAR (50) NOT NULL
);
Insert Information
INSERT INTO `ROUTE` (`RouteID`,`RouteName`,`BoardingStop`,`AlightingStop`)
VALUES (1,"ab","B","C")
Data warehouse table dimRoute
CREATE TABLE DimROUTE (
RouteID INTEGER(4),
RouteName VARCHAR (50) NOT NULL,
BoardingStop VARCHAR (50) NOT NULL,
AlightingStop VARCHAR (50) NOT NULL,
PRIMARY KEY(RouteID)
);
Populate the above table with data from the first table.
You can copy from one table into another table with INSERT INTO ... SELECT. See docs here: http://dev.mysql.com/doc/refman/5.7/en/insert-select.html
You can copy between tables in different databases on the same MySQL instance, provided you have privileges to both database. Just use databasename.tablename syntax:
INSERT INTO warehouse.DimRoute
SELECT * FROM corporate.Route;
If the databases are hosted on different MySQL instances, you can dump data from the corporate instance and import to the data warehouse instance using mysqldump. Since your table is named differently in the data warehouse, this is a little bit tricky.
You could restore the data to its original table name, and then rename the table:
$ mysqldump --host=corporate corp_dbname ROUTE > route-dump.sql
$ mysql --host=datawarehouse dw_dbname < route-dump.sql
$ mysql --host=datawarehouse -e "RENAME TABLE ROUTE TO DimROUTE" dw_dbname
(I'm leaving out user/password options for brevity, but I suggest you use the config file for those.)
You just need a couple of queries to clone a table (with its indexes and keys) then populate it with the records:
CREATE TABLE DimROUTE LIKE ROUTE;
INSERT DimROUTE SELECT * FROM ROUTE;
Demo SQL Fiddle
Yes, you can. The technique you want is called Extract, Transform and Load (ETL). There are a number of tools you can use, which will help you automate and organise the process. Or you can roll your own solution.
It is quite common for reporting databases to be feed by other databases in this fashion.
Is there a proper place to store a high level description of a database? Something along the lines of "This database is used to store XYZ for use by ABC". It's not necessarily information one would need to query, but something that would useful for someone administering the system (i.e. me in a few months when I'm trying to remember what I was trying to accomplish a few months ago.).
This seems like something that someone would have asked before (or information that is readily findable), but none of my searching came up with anything relevant. Most of what I found was for displaying the structure of the database itself.
Comment metadata is not available for MySQL databases, but you can create a table to store some comments: (I have this table in a generic tools database)
-- Create a table to store db name and fields as need.
create table dbinfo(
id int not null primary key auto_increment,
db_name varchar(64) not null collate utf8_bin,
db_comment varchar(255),
unique (db_name)
) default charset utf8;
To fill/update dbinfo table with current databases:
insert into dbinfo (db_name)
select SCHEMA_NAME
from INFORMATION_SCHEMA.SCHEMATA
where SCHEMA_NAME not in (select db_name from dbinfo);
You will only need to maintain dbinfo table until MySQL enables database comments.
i'm sure there is such question at stackoverflow, but i just c't find it :(
I have 2 databases with same data ("developer" database and "production" database).
"production" database is "Live" database - sitve visitors see this data
"developer" database is database where i create new functions at my local server.
I have situation when i add to "developer" database some new tables and some new fields in old tables.
And now i have to copy this new created fields and tables to "production" database (but only structure, data should not be copied and no data at "production" database must be changed).
UPD: Maybe there is solution where i can make database structure dump from developing database and when i import it to production database, it automatically add all new fields from all tables
What functions should i use?
Thanks.
You want alter table: http://dev.mysql.com/doc/refman/5.1/en/alter-table.html
To alter an existing table:
alter table tablename add column newcolumn tinyint(1) default 1 AFTER othercolumn
To create a new table:
CREATE TABLE `newtablename` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`newcolumn` int(10) unsigned NOT NULL,
PRIMARY KEY (`id`),
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
to copy ONLY the structure you can use like:
jcho360> create table t3 like t2;
Query OK, 0 rows affected (0.05 sec).
If you want to copy the content after create the structure you can use :
INSERT INTO t3 SELECT * FROM t2;
if you want to copy with data you can use (without structure, I mean, PK, FK, etc)
mysql> create table t4 as select * from t1;
of course you are able to use backup to restore tables too
if you want to add new column you can use
alter table tablename add column newcolumn vartype;
if you want to use a table from another database you can use queries calling first the database and later the name, like
select * from database.tablename;
remember the user need permission to the other db too.
I need to alter a table (to change the length and type of a column) of a MySQL database.
The problem is that I need to do this from the command line (in Linux) and I don't really know how.
Can anyone help me?
I have root ssh access.
Something like this should do the trick:
Login to mysql:
mysql -u username -p;
enter mysql password
use databasename;
ALTER TABLE `tablename`
MODIFY COLUMN `columnname` varchar(200) NULL DEFAULT NULL AFTER `previouscolumnname`;
The varchar(200) bit is where you would enter the column type and value length like int(11) etc
Remember to be careful changing field types if the table contains data as it may empty the field or cut it down to the new length specified.
Obviously you need to update per your username, database, tablename and type/length:
mysql -u username -p
use database;
alter table `tablename` modify column `columnname` varchar(512);