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Articles on Trending Technologies
Technical articles with clear explanations and examples
How to update multiple rows and left pad values in MySQL?
Use the LPAD() function to left pad values. Let us first create a table −mysql> create table DemoTable -> ( -> Number int -> ); Query OK, 0 rows affected (2.26 secInsert some records in the table using insert command −mysql> insert into DemoTable values(857786); Query OK, 1 row affected (0.26 sec) mysql> insert into DemoTable values(89696); Query OK, 1 row affected (0.16 sec) mysql> insert into DemoTable values(89049443); Query OK, 1 row affected (0.25 secDisplay all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+----------+ | ...
Read MoreChange the column name from StudentName to FirstName in MySQL?
Use CHANGE with ALTER statement. Let us first create a table −mysql> create table DemoTable -> ( -> StudentName varchar(100), -> Age int -> ); Query OK, 0 rows affected (0.84 sec)Now check the description of table −mysql> desc DemoTable;OutputThis will produce the following output −+----------------+--------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +----------------+--------------+------+-----+---------+-------+ | StudentName | varchar(100) | YES | | NULL | | | Age ...
Read MoreFix Drop table view #1051 unknown table error in MySQL
To correctly drop a view, use the below syntax −drop view yourViewName;Let us first create a table −mysql> create table DemoTable -> ( -> Id int -> ); Query OK, 0 rows affected (1.01 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(1001); Query OK, 1 row affected (0.22 sec) mysql> insert into DemoTable values(1002); Query OK, 1 row affected (0.34 sec) mysql> insert into DemoTable values(1003); Query OK, 1 row affected (0.26 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+------+ | ...
Read MoreFind and display duplicate values only once from a column in MySQL
Let us first create a table −mysql> create table DemoTable -> ( -> value int -> ); Query OK, 0 rows affected (0.82 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable values(100); Query OK, 1 row affected (0.10 sec) mysql> insert into DemoTable values(20); Query OK, 1 row affected (0.28 sec) mysql> insert into DemoTable values(10); Query OK, 1 row affected (0.34 sec) mysql> insert into DemoTable values(30); Query OK, 1 row affected (0.24 sec) mysql> insert into ...
Read MoreIf I truncate a table, should I also add indexes?
If you truncate a table, you do not need to add indexes because table is recreated after truncating a table and indexes get added automatically.Let us first create a table −mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> FirstName varchar(20), -> LastName varchar(20) -> ); Query OK, 0 rows affected (0.65 sec)Following is the query to create an index −mysql> create index Index_firstName_LastName on DemoTable(FirstName, LastName); Query OK, 0 rows affected (1.04 sec) Records: 0 Duplicates: 0 Warnings: 0Insert some records in the table using insert command −mysql> ...
Read MoreMySQL query to return a substring after delimiter?
Use SUBSTRING() to return values after delimiter. Let us first create a table −mysql> create table DemoTable -> ( -> Title text -> ); Query OK, 0 rows affected (0.56 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John is good in MySQL, Sam is good in MongoDB, Mike is good in Java'); Query OK, 1 row affected (0.19 sec)Display all records from the table using select statement −mysql> select *from DemoTable;OutputThis will produce the following output −+-------------------------------------------------------------------+ | Title ...
Read MoreMySQL query to conduct a basic search for a specific last name in a column
You can use LIKE operator to conduct a basic search for last name. Let us first create a table: −mysql> create table DemoTable -> ( -> CustomerName varchar(100), -> CustomerAge int -> ); Query OK, 0 rows affected (0.77 sec)Insert some records in the table using insert command −mysql> insert into DemoTable values('John Doe', 34); Query OK, 1 row affected (1.32 sec) mysql> insert into DemoTable values('David Miller', 24); Query OK, 1 row affected (0.18 sec) mysql> insert into DemoTable values('Bob Doe', 27); Query OK, 1 row affected (0.18 sec) mysql> insert into ...
Read MoreCalling NOW() function to fetch current date records in MySQL?
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 (1.16 sec)Insert some records in the table using insert command. Consider current date “2019-06-28” −mysql> insert into DemoTable(ShippingDate) values('2019-01-31'); Query OK, 1 row affected (0.14 sec) mysql> insert into DemoTable(ShippingDate) values('2019-06-06'); Query OK, 1 row affected (0.11 sec) mysql> insert into DemoTable(ShippingDate) values('2019-06-28'); Query OK, 1 row affected (0.20 sec) mysql> insert into DemoTable(ShippingDate) values('2019-07-01'); Query OK, 1 row affected (0.16 sec)Display all records from the table ...
Read MoreHow to use contains() in android CopyOnWriteArraySet?
Before getting into example, we should know what CopyOnWriteArraySet is. It is a thread-safe variant of ArrayList and operations add, set, and so on by making a fresh copy of the underlying array.This example demonstrates about How to use contains () in android CopyOnWriteArraySetStep 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code, we have taken text view to show CopyOnWriteArraySet elements.Step 3 − Add the following code to ...
Read MoreHow to use contains() in android CopyOnWriteArrayList?
Before getting into example, we should know what CopyOnWriteArrayList is. It is a thread-safe variant of ArrayList and operations add, set, and so on by making a fresh copy of the underlying array.This example demonstrates about How to use contains () in android CopyOnWriteArrayListStep 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.Step 2 − Add the following code to res/layout/activity_main.xml. In the above code, we have taken text view to show CopyOnWriteArrayList elements.Step 3 − Add the following code to ...
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