![]() ![]() ![]() How much CPU time it uses (gauged with SET STATISTICS TIME ON)ĭon’t obsess over small differences between the operations – I’m writing this blog post fast & furious to show you the big-picture differences, and to show you how my thought process works when comparing the different operations.How many pages it reads (gauged with SET STATISTICS IO ON).Let’s do an exploration of the Votes table in the Stack Overflow database, specifically the 2018-06 ~300GB version where the Votes table has 150,784,380 rows taking up ~5.3GB of space. However, an empty string is used to point to a unique string with zero length.When you run a SELECT COUNT(*), the speed of the results depends a lot on the structure & settings of the database. The difference is that NULL is used to refer to nothing. ConclusionĪ string refers to a character's sequence. NULL is used when some fields are optional, and the data is unknown. So, NULL is better.Īn empty string is useful when the data comes from multiple resources. However, it will throw an error of unique constraint if you use an empty string here. Since the phone number is a unique field, the user with no phone number will get added. For example, in this case, a phone number is optional. NULL works well when a UNIQUE field is set. The first one could be interpreted as an unknown number, and the second could be interpreted as the user has no phone number. ![]() However, the first query insets a NULL value, and the second inserts an empty string. Use the example below to understand the concept of NULL and empty string: mysql>INSERT into users (phone) VALUES (NULL) Īnd mysql> INSERT into users (phones) VALUES (') īoth statements insert value in the phone column. Then, create a sample users table: mysql> create table users (id BIGINT PRIMARY KEY, name VARCHAR (50), phone VARCHAR (50)) Switch to the database: mysql > use info_db We can use a test database and apply the knowledge in the production environment to understand the concept better.Ĭreate a test database named info_db on the server using the syntax below: mysql>Create database info_db CHARACTER SET utf8 COLLATE utf8_general_ci However, this is not the case.Īn empty string is a string instance of zero length. The concept of NULL and empty string often creates confusion since many people think NULL is the same as a MySQL empty string. Once the state of your instance is running, you can manage it from the console. Note: It will take some time to prepare and launch your instance. The service will be activated as soon as the payment is confirmed: You will be redirected to the order confirmation page: Step 4: Choose the instance configurations and storage types that best suit your requirements:.In the basic configuration section, select the Region and Zones where you want to launch the RDS instance: Step 3: Select your preferred payment method.Then, you will be redirected to the Product Purchase Console: Step 2: Select the Create Instance option to create the RDS instance:.Step 1: Log in to your Alibaba Cloud and navigate to AsparaDB for RDS under the Product and Services section:.How to Launch an RDS Instanceįollow this step-by-step guide to launch an AsparaDB for the RDS instance: This article will help you understand when to use NULL and when to use an empty string in MySQL functions on Alibaba Cloud RDS. MySQL functions handle complex operations, including string formats, mathematical computations, I/O processing, and more. The RDBMS standard library functions are a particular set of routines performing a specific task and returning results quickly. MySQL relational database is widely used by developers due to its advanced features, including various transaction support and built-in functions. Using these values incorrectly or opting for the wrong one can have massively different results. That's not correct because NULL and empty string represent different things in the relational database. Have you ever been confused about when to use NULL and when to use an empty string in a database table? Well, database developers use NULLs and empty strings interchangeably within their databases. ![]()
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