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Articles by karthikeya Boyini
Page 125 of 143
Do Double Equal Sign exist in MySQL?
There is no double equal sign concept. It can be used to compare two values. If you use double equal sign(==) in MySQL, you will get an error message.Let us verify the concept is true or not. Declare a variable −mysql> set @Number=10; Query OK, 0 rows affected (0.00 sec)Now, compare the above variable value with 10. If both the values are same then the result will be 1 otherwise 0.Using double equal sign −mysql> select 10==@Number;This will produce the following output i.e. an error −ERROR 1064 (42000): You have an error in your SQL syntax; check the manual ...
Read MoreChange tinyint default value to 1 in MySQL?
You can use DEFAULT command for this. Following is the syntax −alter table yourTableName change yourColumnName yourColumnName TINYINT(1) DEFAULT 1 NOT NULL;Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, UserName varchar(20), UserAge int, isMarried tinyint(1) ); Query OK, 0 rows affected (0.80 sec)Let us check the description of table −mysql> desc DemoTable;This will produce the following output −+-----------+-------------+------+-----+---------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------+-------------+------+-----+---------+----------------+ | Id ...
Read MoreHow to see spaces in data when selecting with MySQL command line client?
Use quote() function for this. The syntax is as follows −select yourColumnName, quote(yourColumnName) from yourTableName;To understand the concept, let us create a table. The query to create a table is as follows −mysql> create table seeSpacesDemo -> ( -> spaceValue varchar(10) -> ); Query OK, 0 rows affected (0.42 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into seeSpacesDemo values(""); Query OK, 1 row affected (0.70 sec) mysql> insert into seeSpacesDemo values(" "); Query OK, 1 row affected (0.45 sec) mysql> insert into seeSpacesDemo values(" "); Query OK, 1 ...
Read MoreFinding only strings beginning with a number using MySQL Regex?
To find strings beginning with a number, use Regular Expressions. Let us first create a table −mysql> create table DemoTable ( Id varchar(200) ); Query OK, 0 rows affected (0.59 sec)Insert records in the table using insert command −mysql> insert into DemoTable values('123User'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values('_$123User'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values('User123456'); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values('0000User'); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values('&^*User'); Query OK, 1 row affected (0.24 sec)Display records ...
Read MoreMySQL UPDATE using IF condition
The syntax is as follows to perform UPDATE using IF condition in MySQL −update yourTableName set yourColumnName =if(yourColumnName =yourOldValue, yourNewValue, yourColumnName);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table updateIfConditionDemo -> ( -> UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> UserName varchar(20), -> UserAge int -> ); Query OK, 0 rows affected (4 min 0.59 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into updateIfConditionDemo(UserName, UserAge) values('Larry', 23); Query OK, ...
Read MoreFormat date in MySQL to return MonthName and Year?
Use DATE_FORMAT() and set the specifiers to display only the MonthName and Year. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, AdmissionDate date ); Query OK, 0 rows affected (0.69 sec)Insert records in the table using insert command −mysql> insert into DemoTable(AdmissionDate) values('2013-04-21'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(AdmissionDate) values('2014-01-31'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(AdmissionDate) values('2016-09-01'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(AdmissionDate) values('2018-12-12'); Query OK, 1 row affected (0.11 sec) mysql> insert ...
Read MoreHow to change MySQL error message language?
You can use lc_messages to change MySQL error message language. The syntax is as follows −SET lc_messages = 'yourLanguage';To understand the concept, let us create a table with some error and check the error message language.Here, we have set the local message to French. Let us first create a table −mysql> create table errorMessagelanguage -> ( -> Error_MessageId int, -> Error_Message varchar(100), -> );The error message is as follows −ERROR 1064 (42000): Erreur de syntaxe près de ')' à la ligne 5Now you can set the error message to be in English language. The query is ...
Read MoreWhich library can be used to interact with database in JSP?
The JSTL SQL tag library provides tags for interacting with relational databases (RDBMSs) such as Oracle, MySQL, or Microsoft SQL Server.Following is the syntax to include JSTL SQL library in your JSP −Following table lists out the SQL JSTL Tags −S.No.Tag & Description1Creates a simple DataSource suitable only for prototyping2Executes the SQL query defined in its body or through the sql attribute.3Executes the SQL update defined in its body or through the sql attribute.4Sets a parameter in an SQL statement to the specified value.5Sets a parameter in an SQL statement to the specified java.util.Date value.6Provides nested database action elements with ...
Read MoreReturn null for date_format when input is null in MySQL?
Use IF() function to return null for date_format when input is null in MySQL. The syntax is as follows −SELECT IF(yourDateColumnName, date_format(yourDateColumnName, '%d/%m/%Y'), NULL) FROM yourTableName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table returnNullWhenInputIsNullDemo -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> ShippingDate datetime -> ); Query OK, 0 rows affected (1.21 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into returnNullWhenInputIsNullDemo(ShippingDate) values('2019-01-21'); Query OK, 1 row affected ...
Read MoreVerify that MySQL SET FOREIGN KEY CHECKS is set to = 1?
You can verify SET FOREIGN KEY CHECKS is set to = 1 or not with the help of variable@@foreign_key_checks;The syntax is as follows −select @@foreign_key_checks;You can use SHOW VARIABLES command. The syntax is as follows −show variables like 'foreign%';Now you can implement both the syntaxes.Case 1 − Using variable @@foreign_key_checks.The query is as follows −mysql> SELECT @@foreign_key_checks; Here is the output −+----------------------+ | @@foreign_key_checks | +----------------------+ | 1 | +----------------------+ 1 row in set (0.00 sec)Case 2 − Using SHOW commandThe ...
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