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Articles by Samual Sam
Page 145 of 151
Drop a MySQL Table after x hours?
You need to create event to drop table after x hours. The syntax is as follows −CREATE EVENT yourEventName ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL x HOUR DO DROP TABLE IF EXISTS yourTableName;Let us first create a table −mysql> create table DemoTable ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudnetFirstName varchar(20), StudentLastName varchar(20), StudnetAge int ); Query OK, 0 rows affected (0.52 sec)Now implement the above event in order to drop table after 2 hours −mysql> CREATE EVENT drop_table_event_after2HoursDemo ON SCHEDULE AT CURRENT_TIMESTAMP + INTERVAL 2 HOUR DO DROP TABLE IF EXISTS DemoTable; Query OK, ...
Read MoreEmpty string in not-null column in MySQL?
In PHP, the empty string equals to a NULL value, but in MySQL, the case is the different i.e. empty string is not equal to NULL value. To understand the above syntax, let us create a column with NOT NULL constraint while you can insert an empty string.Let us create a table. The query to create a table is as follows −mysql> create table EmptyStringNotNullDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(10) not null, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.83 sec)Now you can insert some records ...
Read MoreSearch for text between delimiters in MySQL?
You need to use LOCATE() along with SUBSTR(). The below syntax will find the word after delimiter. Here, delimiter is colon(:), you can use another i.e. it is up to you. The syntax is as follows −SELECT SUBSTR(yourColumnName, LOCATE(':', yourColumnName)+1, (CHAR_LENGTH(yourColumnName) - LOCATE(':', REVERSE(yourColumnName)) - LOCATE(':', yourColumnName))) AS anyAliasName FROM yourTableName;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table SearchTextBetweenDelimitersDemo -> ( -> ...
Read MoreMySQL Query to get count of unique values?
To count the unique values on a column, you need to use keyword DISTINCT. To understand how it is done, let us create a table. The query to create a table is as follows −mysql> create table UniqueCountByIPAddress -> ( -> Id int NOT NULL AUTO_INCREMENT, -> UserHits int, -> UserIPAddress varchar(50), -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.69 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into UniqueCountByIPAddress(UserHits, UserIPAddress) values(10, '127.0.0.1'); Query OK, 1 row affected (0.20 sec) mysql> insert into ...
Read MoreHow to use Swift to run in background to provide current location?
To get background location in swift we need to go through a few stepsGet the permissions from the user, in your info.plist file add Privacy- Location always andwhen in usage Description, Privacy – When in usage description and add their respective description.After that, you need to import the CoreLocation framework which will enable you to use all the location related libraries and methods. Then you need to get permission from the user to use the location. For that, we need to create a CLLocationManager Object and get authorization.var locationManager: CLLocationManager? override func viewDidLoad() { super.viewDidLoad() ...
Read MoreResolve an error whenever multiple rows are returned in MySQL Benchmark?
You will get an error whenever you return multiple rows in the benchmark. Return a scalar value or single row instead of multiple rows. The syntax is as follows −SELECT yourColumnName FROM yourTableName WHERE yourCondition.To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table UserDemo -> ( -> UserId int, -> UserName varchar(20), -> RegisteredCourse varchar(10) -> ); Query OK, 0 rows affected (0.67 sec)Insert some records in the table using insert command. The query is as follows −mysql> insert into UserDemo values(1, ...
Read MoreMySQL how to declare a datetime variable?
To declare a datetime variable, you need to use a user-defined variable using the SET command. The syntax is as follows −SET @anyVariableName=’yourdatetimeValue’;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table datetimeVariables -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name varchar(10), -> ArrivalDatetime datetime, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.78 sec)Insert some records in the table using insert command. The query to ...
Read MoreResolve usage of quotes ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use?
In MySQL, you can use two different types of quotation marks which is backtick and another is single quotes or double quotes. In this case, maybe you are using single quotes to the column name that’s why you are getting error. You need to use the backtick symbol (` `) instead of single quotes. Backtick can be used with column names while single quotes can be used for strings.To understand the above error, let us create a table. The query to create a table is as follows −mysql> create table Backtick_SymbolDemo -> ( -> Id int NOT NULL ...
Read MoreMySQL "not a variable or NEW pseudo-variable" message. What is this error in my Stored Procedure?
To get rid of this error message, let us see a sample example. But before that let us go through the concept to fix it.Use variable to get the value from stored procedure. The variable will prefix with @ symbol. The syntax is as follows −CALL yourStoredProcedureName(yourParameter1, yourParameter2, ..........N, @yourVariableName);To see the value of variable you need to use select statement. The syntax is as follows −SELECT @yourVariableName;To understand the above syntax, let us create a table and insert some records in the table.The query to create a table is as follows −mysql> create table StoredProcedureDemo -> ( ...
Read MoreMySQL CREATE USER with a variable?
You can use a dynamic query for this. First set the variable name for username and variable name for a password. The syntax is as follows −SET @anyVariableName=’yourUserName’; SET @anyVariableName1=’yourpassword’;Now you can use the CONCAT() function from MySQL. The syntax is as follows −SET @yourQueryName = CONCAT (' CREATE USER "', @anyVariableName, '"@"localhost" IDENTIFIED BY "', @anyVariableName1, '" ' );Let us use the prepared statement PREPARE. The syntax is as follows −PREPARE yourStatementVariableName FROM @yourQueryName;Now you can execute the statement. The syntax is as follows −EXECUTE yourStatementVariableName;Deallocate the above using the DEALLOCATE PREPARE. The syntax is as follows −DEALLOCATE ...
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