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Use the function CONVERT() or Regular Expression. The CONVERT() method converts a value from one datatype to another. This will ecnetually fetch digits for us. Let us see an example. Firstly, we will create a table. mysql> create table textIntoNumberDemo -> ( -> Name varchar(100) -> ); Query OK, 0 rows affected (0.47 sec) Inserting some records. mysql> insert into textIntoNumberDemo values('John-11'); Query OK, 1 row affected (0.11 sec) mysql> insert into textIntoNumberDemo values('John-12'); Query OK, 1 row affected (0.17 sec) mysql> insert into textIntoNumberDemo values('John-2'); Query OK, 1 row affected (0.11 ... Read More
To swap two columns, we can apply the below swapping logic. Add both values and store them into the first column Subtract the first column’s value from the second and store it into the second column. Subtract the first column’s value from the updated second column and store it into the first. The above rule structure is as follows. Suppose, the first column is a and the second column is b. 1. a = a+b; 2. b = a-b; 3. a = a-b; Now we will apply the above rule in order to swap the two ... Read More
To check if the given value is a string or not ,we use the cast() function. If the value is not numeric then it returns 0, otherwise it will return the numeric value. In this way, we can check whether the value is an integer or not. Case 1 − Checking for a string with integers mysql> select cast('John123456' AS UNSIGNED); The following is the output. It shows that the value is not numeric, therefore 0 is returned. +--------------------------------+ | cast('John123456' AS UNSIGNED) | +--------------------------------+ | 0 | +--------------------------------+ 1 row in set, 1 warning (0.00 sec) ... Read More
The die() function can be used to stop the script and can be used to display a message to the end user. It can be used at the right side of the OR ( || ) operator and at left side can be any expression like the eval() function. Case 1 − Using die() function with no parameter The following is the output. Now we can use $! to print the error number and a message to the user in the die() function. Case 2 − Use of $! in the die() function The following is the ... Read More
Some of the popular methods of a Thread class is start, sleep, jon, and abort. Let us see the complete list of methods − Sr.No. Method & Description 1 public void Abort() Raises a ThreadAbortException in the thread on which it is invoked, to begin the process of terminating the thread. Calling this method usually terminates the thread. 2 public static LocalDataStoreSlot AllocateDataSlot() Allocates an unnamed data slot on all the threads. For better performance, use fields that are marked with the ThreadStaticAttribute attribute instead. 3 public static LocalDataStoreSlot AllocateNamedDataSlot(string name) Allocates ... Read More
In the system, the root is defined by another name as well as password. Then the user is created as a root with the help of the create command. This will result in the ERROR 1396. The query for this is given as follows − mysql> create user 'root'@'localhost' identified by 'root123'; After executing the above query, the following error is obtained − ERROR 1396 (HY000): Operation CREATE USER failed for 'root'@'localhost' The user can be created with another name and password successfully. This is given as follows − mysql> create user 'John'@'localhost' identified by ... Read More
We can know that with the help of the column name ‘UPDATED_TIME’ using information_schema.tables with WHERE clause. Let us first create a table for our example. mysql> create table MyISAMTableDemo -> ( -> id int -> ); Query OK, 0 rows affected (0.56 sec) Inserting some records into table. mysql> insert into MyISAMTableDemo values(1); Query OK, 1 row affected (0.72 sec) mysql> insert into MyISAMTableDemo values(2); Query OK, 1 row affected (0.16 sec) Syntax to know the last updated time. SELECT UPDATE_TIME FROM information_schema.tables WHERE TABLE_SCHEMA = 'yourDatabaseName' AND TABLE_NAME = ... Read More
Firstly, let us get the current datetime with the help of the now() function. mysql> select now(); The following is the output. +---------------------+ | now() | +---------------------+ | 2018-11-01 19:55:56 | +---------------------+ 1 row in set (0.00 sec) Syntax to subtract 10 days with the help of DATE_SUB() select DATE_SUB(now(),interval integer_value day ); Applying the above syntax to subtract 10 days from the current datetime. mysql> select DATE_SUB(now(),interval 10 day); Here is the output. +---------------------------------+ | DATE_SUB(now(),interval 10 day) | +---------------------------------+ | 2018-10-22 19:56:07 | +---------------------------------+ 1 row in set (0.00 sec)
MySQL has introduced signals similar to an exception in other languages. Let us first see the syntax of signal. SIGNAL SQLSTATE ' PredefinedValueforSignalError' SET MESSAGE_TEXT = 'AnyMessageInformation'; Above, we have set our own error message text as well. We will apply the above query to get an error message with the help of signals. mysql > SIGNAL SQLSTATE '42927' SET MESSAGE_TEXT = 'Error Generated'; The following is the output of the above query. ERROR 1644 (42927): Error Generated In the above output, ‘42927’ is a SQLSTATE and ‘Error Generated’ is an error message, which we added.
Let us understand the difference between initialization and assignment of values. Declaring an array. int [] n // declaring Initialization Declaring an array does not initialize the array in the memory. When the array variable is initialized, you can assign values to the array. Array is a reference type, so you need to use the new keyword to create an instance of the array. int n= new int[10]; // initialization Let’s assign value. You can assign values to individual array elements, by using the index number − n[0] = 100; n[1] = 200 ... Read More