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MySQL Articles
Page 58 of 355
How to insert current date/time in MySQL?
To insert current date/ time in MySQL, use the now() function. Let us now see an example.At first, we will create a table. The CREATE command is used to create a table.mysql > create table CurrentDateTime -> ( -> CurrentTime datetime -> ); Query OK, 0 rows affected (1.14 sec)Syntax to insert the current date/time with the help of insert command and now()mysql> insert into CurrentDateTime values(now()); Query OK, 1 row affected (0.11 sec)To check that the current date/ time is inserted in the table or not, use the select command.mysql> select *from CurrentDateTime; The following is the output that ...
Read MoreSimulating MySQL's ORDER BY FIELD() in PostgreSQL?
The following is the process to simulate MySQL’s ORDER BY FIELD() in PostgreSQL.We have used an Online Compiler to run PostgreSQL.Let us now see what we did above to get the output.Firstly, we created a table.create table PostgreOrderIdDemo ( countryName varchar(20) );Inserted records with the help of INSERT command.insert into PostgreOrderIdDemo values('IND'); insert into PostgreOrderIdDemo values('US'); insert into PostgreOrderIdDemo values('UK');The following is the syntax in PostgreSQL.SELECT * FROM yourTableName ORDER BY CASE WHEN columnName='IND' THEN 1 WHEN columnName='US' THEN 2 WHEN columnName='UK' THEN 3 ELSE 0 END, columnName;ExampleLet us now use the above syntax to get the output.SELECT * ...
Read MoreHow to store usernames and passwords safely in MySQL database?
To store username and passwords safely in MySQL database, we can use MD5().Let us see an example. First, we will create a table. The CREATE command is used to create a table.mysql> create table UserNameAndPasswordDemo - > ( - > U_Id int(10) unsigned NOT NULL AUTO_INCREMENT, - > UserId varchar(255) DEFAULT NULL, - > UserPassword varchar(255) DEFAULT NULL, - > primary key(U_Id), - > UNIQUE KEY `UserId` (`UserId`) - > ); Query OK, 0 rows affected (0.61 sec)Inserting records and safely storing passwords with the help of MD5().mysql> INSERT INTO UserNameAndPasswordDemo(UserId, UserPassword) VALUES ('John@gg.com', MD5('john123')); Query OK, 1 row affected ...
Read MoreRemove new line characters from rows in MySQL?
The Trim() function is used to remove new line characters from data rows in MySQL. Let us see an example. First, we will create a table. The CREATE command is used to create a table.mysql> create table tblDemotrail - > ( - > id int, - > name varchar(100) - > ); Query OK, 0 rows affected (0.57 sec)Let us now insert some records.mysql> insert into tblDemotrail values(1, 'John '); Query OK, 1 row affected (0.15 sec) mysql> insert into tblDemotrail values(2, ' Carol'); Query OK, 1 row affected (0.32 sec) mysql> insert into tblDemotrail values(3, ' Sam ...
Read MoreShow constraints on table command in MySQL?
You can show constraints on tables with the help of SHOW command. The syntax is as follows −show create table yourTableName;The above command will show all constraints with table ENGINE. Using this, you can even see all the column names and corresponding data types.To understand the above MySQL statement, let us first create a table −mysql> create table ShowConstraintsDemo -> ( -> BookId int not null, -> BookName varchar(200) not null, -> BookAuthor varchar(200) Unique not null, -> Primary key(BookId, BookName) -> ); Query OK, 0 rows affected (1.04 sec)Now you can apply the above syntax in order ...
Read MoreWhat do column flags mean in MySQL Workbench?
In MySQL Workbench, column flags can be used with a column to maintain integrity. The column flags are as follows −PK − Primary KeyNN − NOT NULLBIN − BinaryUN − UnsignedUQ − UniqueZF − Zero FilledG − Generate ColumnAI − Auto IncrementLet us learn about them one by one −PKThis stands for the primary key. It can be used to make the column as a primary key.NNIt is for NOT NULL. Used to enforce the column that it will not insert a NULL value.BINThis stands for Binary. This can be used to store data as a binary string.UNIt is for ...
Read MoreDoes MySQL foreign_key_checks affect the entire database?
The foreign_key_checks are session based. Now, we can say that they are for scope i.e. local or global. Here is an example demo of local or global. Both are scopes and we can set this for session.Let us set the scope −mysql> set foreign_key_checks = 0; Query OK, 0 rows affected (0.00 sec) mysql> set global foreign_key_checks = 0; Query OK, 0 rows affected (0.05 sec)The foreign_key_checks variables are server system variables. Here are some more details −PropertyValueSystem Variableforeign_key_checksScopeGlobal, SessionDynamicYesTypeBooleanDefault ValueONSetting foreign_key_checks to 0It affects data definition statements: DROP SCHEMA drops a schema even if it contains tables that have ...
Read MoreIs it possible to use UPDATE query with LIMIT in MySQL?
Yes, it is possible to use UPDATE query with LIMIT in MySQL. Let us see how.For our example, we will first create a table. The CREATE command is used to create a table.mysql>CREATE table tblUpdateLimit -> ( -> id int, -> name varchar(100) -> ); Query OK, 0 rows affected (0.53 sec)Records are inserted with the help of INSERT command.mysql>INSERT into tblUpdateLimit values(1, 'John'); Query OK, 1 row affected (0.54 sec) mysql>INSERT into tblUpdateLimit values(2, 'Carol'); Query OK, 1 row affected (0.12 sec) mysql>INSERT into tblUpdateLimit values(3, 'Smith'); Query OK, 1 row affected (0.10 sec) mysql>INSERT into ...
Read MoreHow to check similarity between two strings in MySQL?
Similarity between two strings can be checked with the help of ‘strcmp()’ function. Here are the conditions.If both strings are equal, then it returns 0.If first string is less than the second string, it returns -1.If first string is greater than the second string, it returns 1.Here is an example.Case 1 − If both strings are equal.The following is the query.mysql > SELECT STRCMP("demo", "demo");The following is the output of the above query.+------------------------+ | STRCMP("demo", "demo") | +------------------------+ | 0 ...
Read MoreHow to escape single quotes in MySQL?
We can escape single quotes with the help of the SELECT statement. For instance, when single quotes are encountered in a name, eg. “Carol’s”.Let us see the syntax.SELECT ‘SomeValue’;Here is an example that display how to include text with single quotes.mysql> SELECT 'Carol's Taylor.'; The following is the output.+-------------------+ | Carol's Taylor | +-------------------+ | Carol's Taylor | +-------------------+ 1 row in set (0.00 sec)
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