Posts (page 241)
-
4 min readTo create a new MySQL database, you can use the CREATE DATABASE statement in the MySQL command-line interface or through a MySQL management tool such as phpMyAdmin.In the MySQL command-line interface, you would type:CREATE DATABASE database_name;Replace "database_name" with the name you want to give to your new database. Make sure to follow any naming conventions and restrictions for database names in MySQL.
-
5 min readTo return a result value from an asynchronous function in Node.js with MySQL, you can use the await keyword to wait for the query to be executed and then return the result. First, you need to make sure your function is declared as async so you can use await inside it. Then, you can use the mysql package to execute your query and store the result in a variable. Finally, you can return this result value from your async function.
-
3 min readTo get unique values from multiple-column values in MySQL, you can use the DISTINCT keyword in your SELECT query. This will remove any duplicate rows from your result set based on all columns specified in the query. Alternatively, you can use the GROUP BY clause to group the results by specific columns and then select only the unique values. Additionally, you can use the UNION or UNION ALL operator to combine multiple SELECT statements and retrieve unique values from each set.
-
4 min readTo declare pre-computed columns on MySQL, you can use the syntax of a virtual column. In MySQL, a virtual column is a column that does not physically exist in the table but is computed on-the-fly when queried.To declare a pre-computed column, you need to use the GENERATED keyword followed by the expression to compute the value of the column.
-
8 min readTo integrate an Angular app with a MySQL database, you typically need to create a backend server using a technology like Node.js or PHP that will serve as the intermediary between the Angular front end and the MySQL database.You will need to set up API endpoints on the backend server that can receive requests from the Angular app to perform operations on the MySQL database, such as fetching data, creating new entries, updating existing entries, and deleting entries.
-
5 min readTo limit 4 records for every record selected in MySQL, you can use the LIMIT clause along with subqueries. First, you need to select the distinct records you want to limit, and then within a subquery, you can use the LIMIT clause to retrieve only 4 records for each distinct record. For example, you can use a query like this: SELECT * FROM ( SELECT DISTINCT column_name FROM table_name ) AS temp JOIN table_name ON temp.column_name = table_name.
-
3 min readTo extend a list in MySQL with another list, you can use the UNION or UNION ALL operator.The UNION operator is used to combine the result sets of two or more SELECT statements into a single result set, removing any duplicates.The UNION ALL operator also combines the result sets of two or more SELECT statements into a single result set, but it retains duplicates.You can use either of these operators to merge the two lists together.
-
5 min readOne of the best ways to deal with JSON values in MySQL is to use the JSON data type, which was introduced in MySQL 5.7. This allows you to store JSON documents in a structured format within a column.You can also use functions and operators, such as JSON_EXTRACT(), JSON_CONTAINS(), and JSON_MERGE(), to query and manipulate JSON data within your database.Another approach is to utilize the MySQL Document Store, which allows you to store JSON documents in a NoSQL-style format within the database.
-
5 min readTo skip a record if the date is repeating in a MySQL table, you can use a SELECT statement with a GROUP BY clause to identify and filter out duplicate dates. By grouping the records based on the date field, you can then use the HAVING clause to specify that only dates with a count greater than one should be excluded from the result set. This will effectively skip any records with a repeated date in the table when querying the database.
-
4 min readTo create users in a MySQL database, you can use the SQL statement "CREATE USER 'username'@'hostname' IDENTIFIED BY 'password';". This will create a new user with the specified username, hostname, and password. You can also grant specific privileges to the user using the GRANT statement, such as SELECT, INSERT, UPDATE, DELETE, etc. After creating the user, make sure to flush the privileges using the FLUSH PRIVILEGES; statement to apply the changes.
-
9 min readTo upload a PDF file on Flutter to MySQL, you can follow these steps:Use the file_picker package in Flutter to select a PDF file from the device.Convert the selected PDF file to bytes using the flutter/services.dart library.Send the converted PDF file bytes to a backend server using HTTP POST request.In the backend server, handle the HTTP POST request to receive the file bytes.Convert the received file bytes back to a PDF file.
-
4 min readTo use 2 cursors in a MySQL 8 procedure, you can declare and open multiple cursors within the procedure. For example, you can declare two cursor variables, open them by executing your queries, fetch rows from each cursor, and close them when done. You can use separate FETCH statements to retrieve rows from each cursor and process them accordingly within the procedure's body. Remember to handle errors and exceptions that may arise while working with multiple cursors in your MySQL 8 procedure.