Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
Database Articles
Page 134 of 546
When running UPDATE … datetime = NOW(); will all rows updated have the same date/ time in mysql?
The now() function returns the constant time that exhibits the time at which any statement began to execute. The sysdate() function returns the exact same datetime at which it executed the statement from MySQL 5.0.13.Suppose if you are updating datetime with now() in triggers or stored procedure, the now() method returns the time at which time the triggering and stored procedure begin to execute.Here is the demo of update with now(). Let us first create a table. The query to create a table is as follows −mysql> create table NowDemo -> ( -> DueDateTime datetime -> ); Query OK, 0 ...
Read MoreHow to insert date in single quotes with MySQL date formats?
To insert the date with date formats, use the str_to_date() function with date in single quotes. The following is the syntax −insert into yourTableName values(Value1, value2, ......ValueN, str_to_date(‘anyDate’, ’%Y-%m-%d’));Here are the Date Formats in MySQL −FormatDescription%aAbbreviated weekday name (Sun to Sat)%bAbbreviated month name (Jan to Dec)%cNumeric month name (0 to 12)%DDay of the month as a numeric value, followed by suffix (1st, 2nd, 3rd, ...)%dDay of the month as a numeric value (01 to 31)%eDay of the month as a numeric value (0 to 31)%fMicroseconds (000000 to 999999)%HHour (00 to 23)%hHour (00 to 12)%IHour (00 to 12)%iMinutes (00 to 59)%jDay ...
Read MoreHow add unique key to existing table (with non-unique rows)?
You can add unique key to existing table with the help of alter command. The syntax is as follows −ALTER TABLE yourTableName ADD CONSTRAINT yourConstraintName UNIQUE(yourColumnName1, yourColumnName2, ............N);To understand the above concept, let us create a table with some columns. The query to create a table −mysql> create table MovieCollectionDemo −> ( −> MovieId int, −> MovieDirectorName varchar(200), −> NumberOfSongs int unsigned −> ); Query OK, 0 rows affected (0.62 sec)Now you can check the table does not have any unique constraint. The query to check unique constraint is ...
Read MoreGenerating a range of numbers in MySQL?
To generate a range of numbers in MySQL, you can use stored procedure. Firstly, we need to create a table. After that, we will create a stored procedure that generates a range of number from 10 to 1.The following is the query to create a table −mysql> create table GeneratingNumbersDemo −> ( −> Number int −> ); Query OK, 0 rows affected (0.55 sec)Now you can create a stored procedure that stores a range of numbers in the table. The following is the query to create a stored procedure −mysql> delimiter // mysql> CREATE PROCEDURE ...
Read MoreHow to skip first 10 results in MySQL?
To skip first 10 results, use “limit offset”. The syntax is as follows −select *from yourTableName limit 10 offset lastValue;Let us create a table to understand the above syntax. The following is the query to create a table −mysql> create table SkipFirstTenRecords −> ( −> StudentId int, −> StudentName varchar(200) −> ); Query OK, 0 rows affected (0.53 sec)Now you can insert some records in the table with the help of insert command. The query is as follows −mysql> insert into SkipFirstTenRecords values(100, 'John'); Query OK, 1 row affected (0.12 sec) ...
Read MoreMySQL Mass Update with CASE WHEN/ THEN/ ELSE?
The syntax for mass update with CASE WHEN/ THEN/ ELSE is as follows −UPDATE yourTableName set yourColumnName=case when yourColumnName=Value1 then anyUpdatedValue1 when yourColumnName=Value2 then anyUpdatedValue2 when yourColumnName=Value3 then anyUpdatedValue3 when yourColumnName=Value4 then anyUpdatedValue4 else yourColumnName end;To understand the above syntax, let us first create a table. The query to create a table is as follows −mysql> create table CaseUpdateDemo -> ( -> Id int, -> Name varchar(100) -> ); Query OK, 0 rows affected (0.78 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into CaseUpdateDemo values(1, 'John'); Query OK, 1 row affected ...
Read MoreMySQL always returning the bit values as blank? How to get the original values?
To get the original value, use the following syntax −Syntaxselect yourBitColumnName+0 from yourTableName;The above syntax cast the bit column to an integer. To understand the above concept, let us create a table and check how the returning value is blank. We will also see how to get the original value.The query to create a table.mysql> create table BitDemo -> ( -> hasValidId bit not null -> ); Query OK, 0 rows affected (1.21 sec)Insert some records in the table using insert command. The query to insert records is as follows −mysql> insert into BitDemo values(1); Query OK, 1 row affected ...
Read MoreFetching rows added in last hour with MySQL?
You can use date-sub() and now() function from MySQL to fetch the rows added in last hour.SyntaxThe syntax is as follows −select *from yourTableName where yourDateTimeColumnName create table LastHourRecords -> ( -> Id int, -> Name varchar(100), -> Login datetime -> ); Query OK, 0 rows affected (0.67 sec)Insert records in the form of datetime using insert command. The query to insert record is as follows −mysql> insert into LastHourRecords values(1, 'John', ' 2018-12-19 10:00:00'); Query OK, 1 row affected (0.17 sec) mysql> insert into LastHourRecords values(2, 'Carol', '2018-12-19 10:10:00'); Query OK, 1 row affected (0.15 sec) ...
Read MoreQuery in MySQL for string fields with a specific length?
To query for string fields with a specific length, use the char_length() or length() from MySQL.SyntaxThe syntax is as follows −Case 1 − Use of char_length()This can be used when we are taking length in a number of characters.The syntax −select *from yourTableName where char_length(yourColumnName)=anySpecificLengthValue;Case 2 − Use of length()This can be used when we are taking the length in bytes.The syntax −select *from yourTableName where length(yourColumnName)=anySpecificLengthValue;To understand the above concept, let us first create a table. The query to create a table is as follows −mysql> create table StringWithSpecificLength -> ( -> Id int, -> Name varchar(100), -> FavouriteLanguage ...
Read MoreGet the time difference and convert it to hours in MySQL?
You can achieve with the help of timestampdiff() method from MySQL. The syntax is as follows −SyntaxSELECT ABS(TIMESTAMPDIFF(HOUR, yourColumnName1, yourColumnName2)) as anyVariableName from yourTableName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table DifferenceInHours -> ( -> StartDateTime datetime, -> EndDateTime datetime -> ); Query OK, 0 rows affected (0.59 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into DifferenceInHours values('2018-12-20 10:00:00', '2018-12-19 12:00:00'); Query OK, 1 row affected (0.11 sec) mysql> insert into DifferenceInHours ...
Read More