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Articles by Ankith Reddy
Page 67 of 73
How can we use nested transactions in MySQL?
We can work with nested transactions in MySQL with the help of SAVEPOINT.Firstly, create a table. After that, begin the transaction.Now, insert records in the table created above. Use SAVEPOINT statement to set a named transaction savepoint with a name of identifier.Here are all the steps shown in the form of query −Create tablemysql> create table NestedTransactionDemo -> ( -> Name varchar(200) -> ); Query OK, 0 rows affected (0.63 sec)Start the transaction −mysql> START TRANSACTION; Query OK, 0 rows affected (0.00 sec)Now, insert a record in the tablemysql> insert into ...
Read MoreHow to find the MySQL data directory from command line in Windows?
To find the MySQL data directory, we can simply use the variable datadir. Let us see how to use the variable with select statement.The query is as follows −mysql> select @@datadir;Here is the output+---------------------------------------------+ | @@datadir | +---------------------------------------------+ | C:\ProgramData\MySQL\MySQL Server 8.0\Data\ | +---------------------------------------------+ 1 row in set (0.00 sec)Now we can reach the directory from the above sample output.Here is the snapshot that displays the MySQL data directory.
Read MoreIs there a way in MySQL to reverse a boolean field with a single query?
Yes, you can use if() function from MySQL to reverse a boolean field. The syntax is as follows −UPDATE yourTableName SET yourBooleanColumnName = IF(yourBooleanColumnName, 0, 1);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table ReverseBooleanField -> ( -> Id int NOT NULL AUTO_INCREMENT, -> isValid BOOLEAN -> , -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.56 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into ReverseBooleanField(isValid) values(true); ...
Read MoreHow to quote values using MySQL group_concat?
You can quote values using concat() and grop_concat() function from MySQL. The syntax is as follows −SELECT GROUP_CONCAT(CONCAT(' '' ', yourColumnName, ' '' ' )) 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 Group_ConcatDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Value int, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (1.56 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> insert into Group_ConcatDemo(Value) ...
Read MoreMySQL Query a List of Values?
To query a list of values, you can use IN operator. The syntax is as follows −SELECT * FROM yourTableName WHERE yourColumnName IN(Value1, Value2, ...N) ORDER BY FIELD(yourColumnName, Value1, Value2, ...N);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table ListOfValues -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(30), -> Age int, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.72 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert ...
Read MoreHow can I simulate an array variable in MySQL?
Instead of simulating an array variable, use temporary table in MySQL. The syntax is as follows −create temporary table if not exists yourTemporaryTableName select yourColumnName1, yourColumnName2, ......N from yourTableName where conditionTo understand the above syntax, let us first create a table. The query to create a table is as follows −mysql> create table SimulateArrayDemo -> ( -> Id int, -> FirstName varchar(100), -> LastName varchar(100 -> ) -> ); Query OK, 0 rows affected (1.25 sec)Insert some records in the table using ...
Read MoreHow to get ER model of database from server with MySQL Workbench?
To get ER model of database from server, you need to first launch MySQL Workbench. The snapshot is as follows −After that you need to select the “Database” menu −Database->Reverse EngineerAfter that a wizard will open as in the following screenshot. Add the password and press OK twice.After pressing the OK button, you will get the next wizard and you need to press next button. The following would be visible now −After that you need to select “Model” menu as I have marked in the above wizard.Model->Create Diagram from Catalog Objects After selecting the option, you will get the ER ...
Read MoreHow to update RecyclerView Adapter Data in Android?
Before getting into example, we should know what is Recycler view in android. Recycler view is more advanced version of list view and it works based on View holder design pattern. Using recycler view we can show grids and list of items.This example demonstrate about how to update Recycler View adapter by creating a beautiful student records app that displays student name with age.Step 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 − Open build.gradle and add Recycler view & Card view ...
Read MoreIs BIGINT(8) the largest integer MySQL can store?
In BIGINT(8), the number 8 represents how the data will be displayed. It does not affect the storage. The number is used to display width.BIGINT takes 8 bytes i.e. 64 bits. The signed range is -9223372036854775808 to 9223372036854775807 and unsigned range takes positive value. The range of unsigned is 0 to 18446744073709551615.To understand bigint(8), let us create a table with BIGINT(8) and zerofill column −mysql> create table BigIntDemo8 -> ( -> Number1 BIGINT(8) not null, -> Number2 BIGINT(8) unsigned zerofill not null -> ); Query OK, 0 rows ...
Read MoreHow to Stop EditText from gaining focus at Activity startup in Android
There are so many situations where we don't required keyboard visibility when activity starts. This example demonstrate about how to Stop EditText from gaining focus at Activity startupStep 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 given on Edit Text. By Default it contains request focus.Step 3 − Add the following code to src/MainActivity.javapackage com.example.andy.myapplication; import android.os.Bundle; import android.support.v7.app.AppCompatActivity; import android.widget.EditText; public class MainActivity extends ...
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