MySQL HowTos

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What is connection string in MySQL
In this article, we will learn how we can access the data from the MySQL database using the PHP language.
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Connection string is a string that specifies the information related to database login. For understanding, we will consider an example of a PHP scripting language and will write a code to establish the connection with the database. We have a database, named “Organization”, the user name is “maadi” and password is “qwer1234”...
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What is schema in MySQL
The data in MySQL is managed in databases in the form of tables, which further consist of rows and columns. What is Schema? Schema is different from databases as it does not have all the privileges that a database holds, it has only privileges of tables, rows, and columns which defines the structure of a database.
In this write-up, we will explain what a schema is, how it works, and what are the differences between the schema and database.
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What is “IS NULL” query in MySQL
The ‘IS NULL” query in the MySQL database shows the data which is either missing or is unknown to DMS. A NULL value is different as it has no value, it is neither equal to zero integer or to an empty set. Null is a state, not a value, if we compare the NULL value to any other NULL value, the result will always be NULL because it’s unknown itself. A “IS NULL” query is used when data is missing or unknown for example we make a list of phone directories, if any person’s phone number is unknown then “IS NULL” will extract it and the number can later be added to complete the directory.
In this article, we are going to understand what the “IS NULL” query is and how it works with some examples.
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How to use the SELECT INTO TEMP table statement in MySQL
Sometimes, we are supposed to fetch out data from different MySQL tables which we can use for some specific purpose. For our ease, we create a temporary table and place all the data there which we can later use. When the session is over, the table will vanish on its own, else it can delete it using the DROP command. Similarly, to create the clone of the table we use the statement “SELECT INTO”, which not only copies the contents of the selected table but also inserts all the content into the newly created table.
In this write-up, we will learn how to use the statement “SELECT INTO TEMP TABLE” in MySQL and how this statement works.
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How to use mysqli_real_escape_string function
A mysqli_real_escape_string is a built-in function of the PHP that is used to control the unwanted and dangerous characters. In this article, we will discuss with the help of an example what is the mysqli_real_escape_string function and how it can be used for the protection of the database.
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How to use MySQL Substring function
Mysql has a variety of built-in functions for different purposes, one of them is the function of the substring. The function of substring deals with the “string” data type and it is used in database management to extract the string from the tables. Now what the string is? The string is the collective combination of the characters. For example, “Hello LinuxHint” and “KHG1234” are strings.
In this article, we will understand what is the substring function and how it can be used in MySQL in managing the data in the databases.
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How to use MySQL COALESCE function
MySQL is a DBMS that has a concept of Null values. In MySQL, COALESCE function is used as it returns the first non-null value from the specified series of expressions. If all values of the column are null then COALESCE will also return the null. It works similarly to “IS NULL query ”; both deals with the NULL values but the difference in both of them is of their behavior, “IS NULL” query extracts the null values from the table whereas the COALESCE function gives the first non-null value if there is any null value present in the table.
In this write-up, we will explain what COALESCE function is in MySQL and how it can be used with the help of examples.
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