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Articles by karthikeya Boyini
Page 133 of 143
MySQL concat() to create column names to be used in a query?
To create column names to be used in a query, you need to use a user-defined variable with the set command. The syntax is as follows −SET @anyVariableName := ( SELECT CONCAT ( "SELECT", GROUP_CONCAT(CONCAT(" 1 as ", COLUMN_NAME) SEPARATOR ', '), " FROM DUAL") FROM INFORMATION_SCHEMA_COLUMNS WHERE TABLE_NAME= ‘yourTableName’ );Now prepare the statement using the PREPARE command. The syntax is as follows −PREPARE anyVariableName from @anyVariableName;Execute statement using EXECUTE command. The syntax is as follows −EXECUTE anyVariableName;Deallocate the prepared statement using DEALLOCATE command. The syntax is as follows −DEALLOCATE PREPARE anyVariableName; ...
Read MoreImprove MySQL Search Performance with wildcards (%%)?
No, MySQL won’t improve search performance whenever you have leading wildcards because MySQL will be unable to use the index. If you change to ‘anyLetter%’ then it will be able to use indexThe below syntax is better to use with trailing wildcards. The syntax is as follows −SELECT *FROM yourTableName WHERE yoorColumnName LIKE ‘anyLetter%’;The query to create a table is as follows −mysql> create table TrailingWildCardDemo -> ( -> Id int NOT NULL AUTO_INCREMENT, -> Name Varchar(20), -> PRIMARY KEY(Id) -> ); Query OK, 0 ...
Read MoreHow to develop or migrate apps for iPhone 5 screen resolution?
At the release of iPhone 5, it’s resolution and aspect ratio was different (640 x 1136 pixels), hence it was tough to migrate applications from iPhone 4 sizes to the newer iPhone. But later with the release of iOS 8, size classes and abstract screen sizes were also introduced to make it easier. As of now, applications for almost all sizes can be developed with Xcode storyboard editor.Apart from storyboard editor, you can also change the launch image. Let’s see the first method.Change the launch image to Default-568h@2x.png. Change the size to be 1136x640.Go to info.plist and remove the value ...
Read MoreMySQL- GROUP and COUNT by date?
You can use GROUP BY clause and COUNT() function for this. The syntax is as follows −SELECT yourColumnName1, yourColumnName2, ..N, COUNT(*) as anyAliasName FROM yourTableName GROUP BY yourColumnName1, yourColumnName2;To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table GroupAndCountByDate -> ( -> Id int NOT NULL AUTO_INCREMENT, -> TripDate date, -> ShopId int, -> PRIMARY KEY(Id) -> ); Query OK, 0 rows affected (0.79 sec)Now you can insert some records in the table using insert command. The query is as follows −mysql> ...
Read MoreHow to integrate PayU Money in iOS using swift?
payU money is a payment gateway which is more popular in Indian online markets. To Integrate payU money we need to go through a few steps. Be careful with integrating payU and do not skip any of the steps of integration.Sign Up with payU money.Once you sign up, your key & salt, merchant ID will be generated which can be found in the dashboard after you login to your payU money account.After that in the terminal application, use the below code to clone payU money.Drag and drop the PlugNPlay folder to your project.$ git clone --recursive https://github.com/payu-intrepos/PayUMoney-IOS-SDK.gitNote − If you ...
Read MoreReturn order of MySQL SHOW COLUMNS?
To return order of MySQL SHOW COLUMNS, you need to use ORDER BY clause. The syntax is as follows −SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE table_name = ‘yourTableName’ AND column_name LIKE 'yourStartColumnName%' ORDER BY column_name DESC;Let us create a table in database TEST. The query to create a table is as follows −mysql> create table OrderByColumnName -> ( -> StudentId int, -> StudentFirstName varchar(10), -> StudentLastName varchar(10), -> StudentAddress varchar(20), -> StudentAge int, -> StudentMarks int ...
Read MoreShould I store a field PRICE as an int or as a float in the database?
You do not need to store a field PRICE as an int or as float in the database. For this, you can set the DECIMAL()..Most of the time integers can be used to represent the float point numbers and these integers are internally cast into DECIMAL() data type. Therefore, if you have field PRICE then always use DECIMAL() data type. The syntax is as follows −DECIMAL(M, D);Here, M represents the ‘TotalNumberOfDigit’ and D represents the ‘Number OfDigitAfterDecimalPoint’.To understand the above concept, let us create a table with field PRICE as DECIMAL data type. The query is as follows −mysql> create ...
Read MoreUsing LIKE for two where clauses in MySQL?
You don’t need to use two where clauses. Use two conditions using the LIKE operator and AND operator.To understand how to use LIKE for this, let us create a table. The query to create a table is as follows −mysql> create table WhereDemo -> ( -> Id int, -> Name varchar(20) -> ); 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 WhereDemo values(101, 'Maxwell'); Query OK, 1 row affected (0.14 sec) mysql> insert into WhereDemo values(110, 'David'); Query ...
Read MoreExploratory Data Analysis in Python
For data analysis, Exploratory Data Analysis (EDA) must be your first step. Exploratory Data Analysis helps us to −To give insight into a data set.Understand the underlying structure.Extract important parameters and relationships that hold between them.Test underlying assumptions.Understanding EDA using sample Data setTo understand EDA using python, we can take the sample data either directly from any website or from your local disk. I’m taking the sample data from the UCI Machine Learning Repository which is publicly available of a red variant of Wine Quality data set and try to grab much insight into the data set using EDA.import pandas ...
Read MoreCreate MySQL column with Key=MUL?
You need to use ADD KEY to make a column with Key=MUL. The syntax is as follows −ALTER TABLE yourTableName MODIFY COLUMN yourColumnName data type, ADD KEY(yourColumnName);To understand the above syntax, let us create a table. The query to create a table is as follows −mysql> create table Instructor -> ( -> Instructor_Id int, -> Instructor_Name varchar(30), -> Instructor_CourseName varchar(100) -> ); Query OK, 0 rows affected (0.63 sec)Now you can look the table description of the table, the column KEY does not have any MUL key. The query is as follows to check the ...
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