Jammy 
In MySQL, you can use the or != operators to test for inequality in a query. For example, we could test for inequality using the operator, as follows: SELECT * FROM contacts WHERE last_name ‘Johnson’; What does != Mean in a query? means not equal to, != also means not equal to. How do you use not equal to in …
The basic SQL structure is the same — all databases support SELECT , FROM , GROUP BY , and similar constructs. However, there are definitely differences among databases. Much of what you have learned will apply to other databases, but it is worth testing to be sure that it works and does what you intend. How many SQL syntax are …
The ISNULL() function returns 1 or 0 depending on whether an expression is NULL. If expression is NULL, this function returns 1. Otherwise, it returns 0. IS NULL function in MySQL? The ISNULL() function returns 1 or 0 depending on whether an expression is NULL. If expression is NULL, this function returns 1. Otherwise, it returns 0. Is NULL and …
The IS NULL condition is satisfied if the column contains a null value or if the expression cannot be evaluated because it contains one or more null values. If you use the IS NOT NULL operator, the condition is satisfied when the operand is column value that is not null, or an expression that does not evaluate to null. What …
That is why you should not use SELECT * in an SQL query anymore. It’s always better to use the explicit column list in a SELECT query than a * wild card. It not only improves performance but also makes your code more explicit. Why should we not use * in SQL? SELECT * return more data than required to …
The symbol Asterisk (*) in a select query retrieves all data from the table. What does asterisk (*) mean in SQL? The asterisk or star symbol ( * ) means all columns. The semi-colon ( ; ) terminates the statement like a period in sentence or question mark in a question. What does an asterisk (*) indicate? An asterisk is …
C:\Program Files\Microsoft SQL Server\MSSQL{nn}. How do I find the location of a database? If you ever need to know where your database files are located, run the following T-SQL code: USE master; SELECT name ‘Logical Name’, physical_name ‘File Location’ FROM sys. master_files; This will return a list of all data files and log files for the SQL Server instance. Where …
A wildcard character is used to substitute one or more characters in a string. Wildcard characters are used with the LIKE operator. The LIKE operator is used in a WHERE clause to search for a specified pattern in a column. What does the * wildcard mean in SQL? A wildcard character is used to substitute one or more characters in …
MySQL Wildcards A wildcard character is used to substitute one or more characters in a string. Wildcard characters are used with the LIKE operator. The LIKE operator is used in a WHERE clause to search for a specified pattern in a column. What are wildcards in database? A wildcard is a character that substitutes for another character or string of …
The second part of a SQL query is the name of the column you want to retrieve for each record you are getting. You can obviously retrieve multiple columns for each record, and (only if you want to retrieve all the columns) you can replace the list of them with * , which means “all columns”. What do * mean …