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MySQL Articles
Page 6 of 355
How to easily insert datetime in MySQL?
You can easily insert DateTime with the MySQL command line. Following is the syntax − insert into yourTableName values(‘yourDateTimeValue’); Let us first create a table − mysql> create table DemoTable ( DateOfBirth datetime ); Query OK, 0 rows affected (0.97 sec) Insert some records in the table using insert command − mysql> insert into DemoTable values('1998-01-23 12:45:56'); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable values('2010-12-31 01:15:00'); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values('2015-04-03 14:00:45'); Query OK, 1 row affected (0.10 sec) Display all records from the table using select statement ...
Read MoreHow to store and retrieve a date into MySQL database using Python?
To insert a date in a MySQL database, you need to have a column of Type date or datetime in your table. Once you have that, you'll need to convert your date in a string format before inserting it to your database. To do this, you can use the datetime module's strftime formatting function.Example from datetime import datetime now = datetime.now() id = 1 formatted_date = now.strftime('%Y-%m-%d %H:%M:%S') # Assuming you have a cursor named cursor you want to execute this query on: cursor.execute('insert into table(id, date_created) values(%s, %s)', (id, formatted_date))Running this will try to insert the tuple (id, date) ...
Read MoreHow can we capitalize only first letter of a string with the help of MySQL function/s?
Actually, there is no single function in MySQL to capitalize only first letter of the string. We need to use nesting of functions and for this case, we can use UPPER() and LOWER() with SUBSTRING() functions. To understand it, we are using data, given as below, from ‘emp_tbl’.mysql> Select * from emp_tbl; +----+----------------+ | Id | Name | +----+----------------+ | 1 | rahul singh | | 2 | gaurav kumar | | 3 | yashpal sharma | | 4 | krishan kumar | | 5 | kuldeep rai | | 6 | ...
Read MoreHow to count the number of tables in a MySQL database?
To count the total number of tables, use the concept of count(*) with table_schema. First, to check how many tables are present in our database "business", we need to use the 'show' command. mysql> show tables; The following is the output that displays all the tables in the database "business". +--------------------------+ | Tables_in_business | +--------------------------+ | addcheckconstraintdemo | | addcolumntable | | addconstraintdemo | | addnotnulldemo ...
Read MoreHow to get the next auto-increment id in MySQL?
MySQL has the AUTO_INCREMENT keyword to perform auto-increment. The starting value for AUTO_INCREMENT is 1, which is the default. It will get increment by 1 for each new record. To get the next auto increment id in MySQL, we can use the function last_insert_id() from MySQL or auto_increment with SELECT. Creating a table, with "d" as auto-increment. mysql> create table NextIdDemo -> ( -> id int auto_increment, -> primary key(id) -> ); Query OK, 0 rows affected (1.31 sec) Inserting records into the table. mysql> insert into NextIdDemo ...
Read MoreHow to select last 10 rows from MySQL?
To select last 10 rows from MySQL, we can use a subquery with SELECT statement and Limit concept. The following is an example. Creating a table. mysql> create table Last10RecordsDemo -> ( -> id int, -> name varchar(100) -> ); Query OK, 0 rows affected (0.75 sec) Inserting records into the table. mysql> insert into Last10RecordsDemo values(1, 'John'), (2, 'Carol'), (3, 'Bob'), (4, 'Sam'), (5, 'David'), (6, 'Taylor'); Query OK, 6 rows affected (0.12 sec) Records: 6 Duplicates: 0 Warnings: 0 mysql> insert into Last10RecordsDemo ...
Read MoreHow to cast from VARCHAR to INT in MySQL?
To cast VARCHAR to INT, we can use the cast() function from MySQL. Here is the syntax of cast() function. cast(anyValue as dataType) For our example, we will create a table with the help of CREATE command. mysql> create table VarchartointDemo -> ( -> Value varchar(100) -> ); Query OK, 0 rows affected (0.51 sec) After creating a table, let us insert some records into the table with the help of INSERT command. The query is as follows − mysql> insert into VarchartointDemo values('123'); Query OK, 1 row affected (0.26 sec) ...
Read MoreBest way to test if a row exists in a MySQL table
To test whether a row exists in a MySQL table or not, use exists condition. The exists condition can be used with subquery. It returns true when row exists in the table, otherwise false is returned. True is represented in the form of 1 and false is represented as 0.For better understanding, firstly we will create a table with the help of CREATE command. The following is the query to create a table −mysql> CREATE table ExistsRowDemo -> ( -> ExistId int, -> Name varchar(100) -> ); Query OK, 0 rows affected (0.53 sec)After creating the table successfully, we will ...
Read MoreTypes of dependencies in DBMS
Dependencies in DBMS is a relation between two or more attributes. It has the following types in DBMS −Functional DependencyFully-Functional DependencyTransitive DependencyMultivalued DependencyPartial DependencyLet us start with Functional Dependency −Functional DependencyIf the information stored in a table can uniquely determine another information in the same table, then it is called Functional Dependency. Consider it as an association between two attributes of the same relation.If P functionally determines Q, thenP -> QLet us see an example −EmpIDEmpNameEmpAgeE01Amit28E02Rohit31In the above table, EmpName is functionally dependent on EmpID because EmpName can take only one value for the given value of EmpID:EmpID -> EmpNameThe same is displayed ...
Read MoreHow to select first 10 elements from a MySQL database?
To select first 10 elements from a database using SQL ORDER BY clause with LIMIT 10.The syntax is as followsSELECT *FROM yourTableName ORDER BY yourIdColumnName LIMIT 10;To understand the above syntax, let us create a table. The query to create a table is as followsmysql> create table Clients - > ( - > Client_Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, - > ClientName varchar(20) - > ); Query OK, 0 rows affected (0.51 sec)Insert some records in the table using INSERT command.The query is as followsmysql> insert into Clients(ClientName) values('Larry'); Query OK, 1 row affected (0.09 ...
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