How to change mysql to postgres - mysql

as in title any one can help me with conversion from mysql to postgres
ALTER TABLE tbl_roles MODIFY 'roleId' tinyint(4) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=4;
and the second one
ALTER TABLE tbl_users MODIFY 'userId' int(11) NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=20;
with error syntax error at near "MODIFY"


i did in a different way
CREATE TABLE IF NOT EXISTS tbl_roles (
roleId tinyint(4) NOT NULL PRIMARY KEY AUTO_INCREMENT,AUTO_INCREMENT=4
);
also in table in second table
CREATE TABLE IF NOT EXISTS tbl_users (
userId int(11) PRIMARY KEY NOT NULL AUTO_INCREMENT,AUTO_INCREMENT=20,
);
and there is no errors

Related

Auto Increment missing in my users table after importing on production. How should I modify it?

When I run this query :
ALTER TABLE `users` MODIFY `id` bigint(20) UNSIGNED NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=56;
It gives me error like :
#1833 - Cannot change column 'id': used in a foreign key constraint
'designation_user_user_id_foreign' of table
'databasename.designation_user'

Found a solution that worked!
I made id column in users table unique using more option in action column of users table and then executed below query :
ALTER TABLE `users` MODIFY `id` bigint(20) UNSIGNED NOT NULL AUTO_INCREMENT;

How to use more than 1 auto-increment column in MySQL

I want to create a table name Users where I should have have columns User, cookieID, sessionID, Geo and then I want to first three columns to have some random unique value assigned automatically. I tried to make all three columns AUTO_INCREMENT with User column PRIMARY and 'cookieIDandsessionIDcolumnUNIQUE`. The SQL code is:
CREATE TABLE `users` ( `User` VARCHAR(20) NOT NULL AUTO_INCREMENT ,
`cookieID` INT(20) NULL DEFAULT NULL AUTO_INCREMENT ,
`sessionID` INT(20) NULL DEFAULT NULL AUTO_INCREMENT ,
`Geo` VARCHAR(30) NULL DEFAULT NULL ,
PRIMARY KEY (`User`), UNIQUE (`cookieID`), UNIQUE (`sessionID`), UNIQUE (`Geo`));
But, it did not work because only one column can be declared as AUTO_INCREMENT which must be PRIMARY.
What is the another approach to do this?

Since the auto-increment cannot be applied to multiple to rows and there no option for sequence in MySQL. You can use triggers for the unique update of the row with datetime.
Change to table creation to be of single auto-increment row.
CREATE TABLE `users` ( `User` VARCHAR(20) NOT NULL,
`cookieID` INT(20) NULL DEFAULT NULL,
`sessionID` INT(20) NULL DEFAULT NULL AUTO_INCREMENT ,
`Geo` VARCHAR(30) NULL DEFAULT NULL,
PRIMARY KEY (`User`), UNIQUE (`cookieID`), UNIQUE (`sessionID`), UNIQUE (`Geo`));
Create a trigger on the same table as below. You can set the unique values under the SET for as many column as you want.
CREATE DEFINER=`root`#`localhost` TRIGGER `users_BEFORE_INSERT` BEFORE INSERT ON `users` FOR EACH ROW BEGIN
SET
NEW.cookieID = (SELECT curdate()+curtime());
END
Now when you insert into the table as below.
insert into `users`(`User`) values("test");
You table looks like this.
User cookieID sessionID Geo
test 20315169 0 NULL

If the value which are auto incrementing, you wanna keep both values the same. Then copy the value of one column to another during insertion time of new value.

How to optimize a MySQL select with rows that do not have matching values in the other table

This question is more or less the same as this one: MySQL select rows that do not have matching column in other table; however, the solution there is not not practical for large data sets.
This table has ~120,000 rows.
CREATE TABLE `tblTimers` (
`TimerID` int(11) NOT NULL,
`TaskID` int(11) NOT NULL,
`UserID` int(11) NOT NULL,
`StartDateTime` datetime NOT NULL,
`dtStopTime` datetime NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
ALTER TABLE `tblTimers`
ADD PRIMARY KEY (`TimerID`);
ALTER TABLE `tblTimers`
MODIFY `TimerID` int(11) NOT NULL AUTO_INCREMENT;
This table has about ~70,000 rows.
CREATE TABLE `tblWorkDays` (
`WorkDayID` int(11) NOT NULL,
`TaskID` int(11) NOT NULL,
`UserID` int(11) NOT NULL,
`WorkDayDate` date NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=utf8;
ALTER TABLE `tblWorkDays`
ADD PRIMARY KEY (`WorkDayID`);
ALTER TABLE `tblWorkDays`
MODIFY `WorkDayID` int(11) NOT NULL AUTO_INCREMENT;
tblWorkDays should have one line per TaskID per UserID per WorkDayDate, but due to a bug, a few work days are missing despite there being timers for those days; so, I am trying to create a report that shows any timer that does not have a work day associated with it.
SELECT A.TimerID FROM tblTimers A
LEFT JOIN tblWorkDays B ON A.TaskID = B.TaskID AND A.UserID = B.UserID AND DATE(A.StartDateTime) = B.WorkDayDate
WHERE B.WorkDayID IS NULL
Doing this causes the server to time out; so, I am looking for if there is a way to do this more efficiently?

You don't have any indexes on the columns you're joining on, so it has to do full scans of both tables. Try adding the following:
ALTER TABLE tblTimers ADD INDEX (TaskID, UserID);
ALTER TABLE tblWorkDays ADD INDEX (TaskID, UserID);

Set not null attribute to a existing column

I create my borrowed table that keeps which users borrowed which books records of a library application.
I forgot to set not null When i create userID and bookID fields,
how i can add this feature ti this two fields?
I try this but failed:
Alter table borrowed set not null (userID,bookID);

In mysql you can add a costraint in an existing column with the command MODIFY:
ALTER TABLE borrowed MODIFY userID INT(11) NOT NULL;
ALTER TABLE borrowed MODIFY bookID INT(11) NOT NULL;

You can do so by using the CHANGE syntax separated by comma for multiple columns
ALTER TABLE `borrowed`
CHANGE `userID` `userID` INT(11) NOT NULL,
CHANGE `bookID` `bookID` INT(11) NOT NULL;

What is the best way to have a varchar primary key column with an auto-increment?

I would like to create some tables in MySQL. One table would be for users, one for topics, one for comments, and so on.
I need each table to have its own ID column in the following format:
USERS table: ID column
Values:
USR00001
USR00002
USR00003
..
..
USR99999
where as topics table would have IDs like:
TPC00001
TPC00002
TPC00003
similarly, the comments table would have the following IDs:
CMT00001
CMT00002
I tried to use UNIQUE key but did not work: (inspired by this answer)
CREATE TABLE `users` (
`ID` BIGINT(20) UNSIGNED NOT NULL AUTO_INCREMENT ,
`firstname` VARCHAR(100) NOT NULL ,
`lastname` VARCHAR(100) NOT NULL ,
`email` VARCHAR(100) NOT NULL ,
PRIMARY KEY (`ID`)
UNIQUE KEY ( 'USR' + `ID`)
);
Can it be done using triggers (Before Insert) maybe?
Please note that I don't want to handle the insertion of the primary keys on the application level. I would prefer the database engine to handle all the work for that.