Database - Read For Learn

phpmyadmin #1045 Cannot log in to the MySQL server. after installing mysql command line client

In case MySQL Server is up but you are still getting the error: For anyone who still have this issue, I followed awesome tutorial http://coolestguidesontheplanet.com/get-apache-mysql-php-phpmyadmin-working-osx-10-9-mavericks/ However i still got #1045 error. What really did the trick was to change localhost to 127.0.0.1 at your config.inc.php. Why was it failing if locahost points to 127.0.0.1? I don’t know. But it worked. ===== … Read more

How to display databases in Oracle 11g using SQL*Plus

You can think of a MySQL “database” as a schema/user in Oracle. If you have the privileges, you can query the DBA_USERS view to see the list of schemas:

MySQL error: key specification without a key length

The error happens because MySQL can index only the first N chars of a BLOB or TEXT column. So The error mainly happens when there is a field/column type of TEXT or BLOB or those belong to TEXT or BLOB types such as TINYBLOB, MEDIUMBLOB, LONGBLOB, TINYTEXT, MEDIUMTEXT, and LONGTEXT that you try to make a primary key or index. With full BLOB or TEXT without the length value, MySQL is unable to guarantee … Read more

How to order by with union in SQL?

Just write the order by is applied to the complete resultset

SQL Parentheses use in an OR clause

Take a look at the Operator Precedence in SQL Server (You’ve not specified that, but I’d imagine it’s the same for all RDBMS). What this means is that ANDs (without parenthesis) are evaluated before1 bind more tightly than ORs. So in your specific case, without the parenthesis, the conditions are: employe.service=service.code_serv AND employe.nom LIKE ‘A%’ OR employe.nom LIKE ‘B%’ … Read more

Query to convert from datetime to date mysql

Try to cast it as a DATE

MySQL starts with searching issue

Underscore is a wildcard for a single character. You will need to change your SQL to something like: Or you can escape the underscore

How do I reset a sequence in Oracle?

Here is a good procedure for resetting any sequence to 0 from Oracle guru Tom Kyte. Great discussion on the pros and cons in the links below too. From this page: Dynamic SQL to reset sequence valueAnother good discussion is also here: How to reset sequences?

How to divide two columns?

Presumably, those columns are integer columns – which will be the reason as the result of the calculation will be of the same type. e.g. if you do this: you will get 0, which is obviously not the real answer. So, convert the values to e.g. decimal and do the calculation based on that datatype … Read more

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