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Articles on Trending Technologies
Technical articles with clear explanations and examples
ERROR 1396 (HY000): Operation CREATE USER failed for 'root'@'localhost'?
In the system, the root is defined by another name as well as password. Then the user is created as a root with the help of the create command. This will result in the ERROR 1396. The query for this is given as follows − mysql> create user 'root'@'localhost' identified by 'root123'; After executing the above query, the following error is obtained − ERROR 1396 (HY000): Operation CREATE USER failed for 'root'@'localhost' The user can be created with another name and password successfully. This is given as follows − mysql> create user 'John'@'localhost' identified by ...
Read MoreHow can I tell when a MySQL table was last updated?
We can know that with the help of the column name ‘UPDATED_TIME’ using information_schema.tables with WHERE clause. Let us first create a table for our example. mysql> create table MyISAMTableDemo -> ( -> id int -> ); Query OK, 0 rows affected (0.56 sec) Inserting some records into table. mysql> insert into MyISAMTableDemo values(1); Query OK, 1 row affected (0.72 sec) mysql> insert into MyISAMTableDemo values(2); Query OK, 1 row affected (0.16 sec) Syntax to know the last updated time. SELECT UPDATE_TIME FROM information_schema.tables WHERE TABLE_SCHEMA = 'yourDatabaseName' AND TABLE_NAME = ...
Read MoreHow to subtract 10 days from the current datetime in MySQL?
Firstly, let us get the current datetime with the help of the now() function. mysql> select now(); The following is the output. +---------------------+ | now() | +---------------------+ | 2018-11-01 19:55:56 | +---------------------+ 1 row in set (0.00 sec) Syntax to subtract 10 days with the help of DATE_SUB() select DATE_SUB(now(),interval integer_value day ); Applying the above syntax to subtract 10 days from the current datetime. mysql> select DATE_SUB(now(),interval 10 day); Here is the output. +---------------------------------+ | DATE_SUB(now(),interval 10 day) | +---------------------------------+ | 2018-10-22 19:56:07 | +---------------------------------+ 1 row in set (0.00 sec)
Read MoreHow to raise an error within MySQL?
MySQL has introduced signals similar to an exception in other languages. Let us first see the syntax of signal. SIGNAL SQLSTATE ' PredefinedValueforSignalError' SET MESSAGE_TEXT = 'AnyMessageInformation'; Above, we have set our own error message text as well. We will apply the above query to get an error message with the help of signals. mysql > SIGNAL SQLSTATE '42927' SET MESSAGE_TEXT = 'Error Generated'; The following is the output of the above query. ERROR 1644 (42927): Error Generated In the above output, ‘42927’ is a SQLSTATE and ‘Error Generated’ is an error message, which we added.
Read MoreMySQL pagination without double-querying?
To work with MySQL pagination, firstly let us see how to use CREATE command and use it to create a table. mysql>CREATE table RowCountDemo -> ( -> ID int, -> Name varchar(100) -> ); Query OK, 0 rows affected (0.95 sec) Records are inserted with the help of INSERT command. mysql>INSERT into RowCountDemo values(1, 'Larry'); Query OK, 1 row affected (0.15 sec) mysql>INSERT into RowCountDemo values(2, 'John'); Query OK, 1 row affected (0.13 sec) mysql>INSERT into RowCountDemo values(3, 'Bela'); Query OK, 1 row ...
Read MoreHow to add super privileges to MySQL database?
Firstly, check the MySQL database with DESC command. mysql>DESC mysql.db; The following is the output. +-----------------------+---------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-----------------------+---------------+------+-----+---------+-------+ | Host | char(60) | NO | PRI | | ...
Read MoreGet the new record key ID from MySQL insert query?
We can get new record key with the help of LAST_INSERT_ID() function from MySQL. First, we will create a table and for inserting record, we will use LAST_INSERT_ID(). Let us create a table with the help of create command. The query is as follows − mysql> create table LastInsertRecordIdDemo -> ( -> id int auto_increment, -> value varchar(100), -> primary key(id) -> ); Query OK, 0 rows affected (0.52 sec) After creating a table, we will insert records and set it using LAST_INSERT_ID() ...
Read MoreSorting varchar field numerically in MySQL?
‘LPAD(lower(column_name))’ is used to sort the varchar field numerically in MySQL. Let us see an example. Firstly, we will create a table. The CREATE command is used to create a table. mysql> create table SortingvarcharDemo -> ( -> List varchar(10) -> ); Query OK, 0 rows affected (0.82 sec) Records are inserted with the help of INSERT command. mysql> insert into SortingvarcharDemo values("99"); Query OK, 1 row affected (0.12 sec) mysql> insert into SortingvarcharDemo values("9"); Query OK, 1 row affected (0.17 sec) mysql> insert into SortingvarcharDemo ...
Read MoreUsage of backtick in SQL statements?
The backtick can be used in MySQL. To create a table, we can put table_name in backticks. Example of Backtick in MySQL. The CREATE command is used to create a table. Here, we have added the table name using the backtick symbol. mysql> create table `backtickSymbol` -> ( -> uniId int -> ); Query OK, 0 rows affected (1.65 sec) Records are inserted with the help of INSERT command. mysql> insert into `backtickSymbol` values(1); Query OK, 1 row affected (0.20 sec) mysql> insert into `backtickSymbol` values(2); Query ...
Read MoreFind rows that have the same value on a column in MySQL?
First, we will create a table and insert some values into the table. Let us create a table. mysql> create table RowValueDemo -> ( -> Name varchar(100) -> ); Query OK, 0 rows affected (0.69 sec) Insert records using the insert command. We have added duplicate values as well for our example. mysql> insert into RowValueDemo values('John'); Query OK, 1 row affected (0.14 sec) mysql> insert into RowValueDemo values('Bob'); Query OK, 1 row affected (0.14 sec) mysql> insert into RowValueDemo values('Carol'); Query OK, 1 row affected ...
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