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MySQL Articles
Page 250 of 355
How to get the primary key “column name” of a specific table in MySQL?
Let us first create a table wherein we have a Primary Key CustomerId −mysql> create table DemoTable ( CustomerId int NOT NULL AUTO_INCREMENT, CustomerName varchar(20), CustomerAge int, CustomerCountryName varchar(100), PRIMARY KEY(CustomerId) ); Query OK, 0 rows affected (0.94 sec)Following is the query to get the primary key “column name” of a specific table in MySQL −mysql> SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.KEY_COLUMN_USAGE WHERE TABLE_NAME = 'DemoTable' AND CONSTRAINT_NAME = 'PRIMARY';This will produce the following output −+-------------+ | COLUMN_NAME | +-------------+ | CustomerId | +-------------+ 1 row in set, 2 warnings (0.12 sec)
Read MoreWhat is the equivalent of EXCEPT in MySQL?
You cannot use EXCEPT in MySQL, instead use the NOT IN operator. Let us first create a table −mysql> create table DemoTable ( Number1 int ); Query OK, 0 rows affected (0.71 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(100); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values(200); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable values(300); Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement −mysql> select * from DemoTable;This will produce the following output −+---------+ | ...
Read MoreWhy I am facing a problem using the field 'from' in SQL query?
You cannot use from as a column name directly because from is a reserved word in MySQL. To avoid this, you need to use backtick symbol. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, `from` varchar(100), Name varchar(10) ); Query OK, 0 rows affected (0.92 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(`from`, Name) values('US', 'John'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(`from`, Name) values('UK', 'Carol'); Query OK, 1 row affected (0.14 sec) mysql> ...
Read MoreExcept not working in MySQL?
You cannot use except in MySQL. You can work with NOT IN operator to get the same result. Let us first create a table −mysql> create table DemoTable1 ( Number1 int ); Query OK, 0 rows affected (0.71 sec)Insert some records in the table using insert command −mysql> insert into DemoTable1 values(100); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable1 values(200); Query OK, 1 row affected (0.13 sec) mysql> insert into DemoTable1 values(300); Query OK, 1 row affected (0.13 sec)Display all records from the table using select statement:mysql> select *from DemoTable1This will produce the following output −+---------+ | Number1 | +---------+ | 100 | | 200 | | 300 | +---------+ 3 rows in set (0.00 sec)Following ...
Read MoreTake off last character if a specific one exists in a string?
You can use trim() for this.Let us first create a table −mysql> create table DemoTable ( UserId varchar(100) ); Query OK, 0 rows affected (0.63 sec)Insert some records in the table using insert command. Here, we have added a question mark (?) to the end of some of the strings −mysql> insert into DemoTable values('User123?'); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('User777'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable values('User456'); Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable values('User133?'); Query OK, 1 ...
Read MoreWhat is the Java equivalent to MySQL's smallint?
The short is equivalent to MySQL’s small int. The Java short takes 2 bytes that has the range -32768 to 32767 while MySQL smallint also take 2 bytes with same range.Here is the demo code of short in Java −public class SmallIntAsShortDemo { public static void main(String[] args) { short value = 32767; System.out.println(value); value = -32768; System.out.println(value); // value = 32768; // System.out.println(value); } }The snapshot is as follows −This will produce the following output −32767 -32768Here is the snapshot of the output we ran in EclipseIDE −The MySQL smallint takes 2 bytes with same range.
Read MoreCreate a stored Procedures using MySQL Workbench?
Let us first create a Stored Procedure. Following is the query to create a stored procedure using MySQL Workbench.use business; DELIMITER // DROP PROCEDURE IF EXISTS SP_GETMESSAGE; CREATE PROCEDURE SP_GETMESSAGE() BEGIN DECLARE MESSAGE VARCHAR(100); SET MESSAGE="HELLO"; SELECT CONCAT(MESSAGE, ' ', 'MYSQL!!!!'); END // DELIMITER ;Here is the screenshot of stored procedure in MySQL workbench −You need to execute the above stored procedure with the help of below symbol shown in the screenshot −Now you can call the stored procedure with the help of CALL command.call SP_GETMESSAGE();The screenshot is as follows −Now again you can execute the above statement with the ...
Read MoreMySQL search results by month in format 2015-07-01 11:15:30?
Use MONTH() and YEAR() for this. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, ShippingDate datetime ); Query OK, 0 rows affected (0.54 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(ShippingDate) values('2019-01-21 10:40:21'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(ShippingDate) values('2015-07-01 11:15:30'); Query OK, 1 row affected (0.12 sec) mysql> insert into DemoTable(ShippingDate) values('2012-12-31 10:45:56'); Query OK, 1 row affected (0.14 sec)Display all records from the table ...
Read MoreImplement GREATEST() in MySQL and update the table?
Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Number int ); Query OK, 0 rows affected (0.64 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Number) values(10); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable(Number) values(50); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable(Number) values(100); Query OK, 1 row affected (0.21 sec) mysql> insert into DemoTable(Number) values(190); Query OK, 1 row affected (0.12 sec)Display all ...
Read MorePerform multiplication in SELECT depending on column value in MySQL?
You can use CASE statement for this. Let us first create a table −mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, Value1 int, Value2 int ); Query OK, 0 rows affected (0.76 sec)Insert some records in the table using insert command −mysql> insert into DemoTable(Value1, Value2) values(10, 5); Query OK, 1 row affected (0.09 sec) mysql> insert into DemoTable(Value1, Value2) values(20, 0); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable(Value1, Value2) values(40, 10); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable(Value1, Value2) ...
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