NULL values are not allowed. If the column(s) contain NULL values, the system will not add the primary key constraint. Why should a primary key not be NULL? If two records of a single column have a NULL value, the column values are not considered equal. In simple words two NULL values are not considered as equal. This is the …
A unique key in SQL is the set of fields or columns of a table that helps us uniquely identify records. The unique key guarantees the uniqueness of the columns in the database. It is similar to the primary key but can accept a null value, unlike it. What is a unique key in SQL? The UNIQUE constraint ensures that …
You can get a list of the schemas using an SSMS or T-SQL query. To do this in SSMS, you would connect to the SQL instance, expand the SQL database and view the schemas under the security folder. Alternatively, you could use the sys. schemas to get a list of database schemas and their respective owners. How can I see …
means NOT EQUAL TO, != also means NOT EQUAL TO. Does != Work in SQL? The SQL Not Equal comparison operator (!=) is used to compare two expressions. For example, 15 != 17 comparison operation uses SQL Not Equal operator (!=) between two expressions 15 and 17. What is meant by in SQL query? The symbol in MySQL is same …
In MySQL, the MATCH() function performs a full-text search. It accepts a comma separated list of table columns to be searched. What RegEx does MySQL use? MySQL supports another type of pattern matching operation based on the regular expressions and the REGEXP operator. It provide a powerful and flexible pattern match that can help us implement power search utilities for …
%s is a placeholder used in functions like sprintf. What does %s mean in MySQL? %s is a placeholder used in functions like sprintf. What is %s and %D in MySQL? 12 years, 11 months ago. it’s for php to know how to handle the parameters, %d – the argument is treated as an integer, and presented as a (signed) …
These are explained as following below. @@SERVERNAME : This is used to find the name of the machine/computer on which SQL Server is running. Example – Select @@servername. What is the use of @@ in SQL? @@ is used to prefix internal statistical and metadata functions that return information about how the SQL Server is configured, not specific to any …
12 years, 11 months ago. it’s for php to know how to handle the parameters, %d – the argument is treated as an integer, and presented as a (signed) decimal number. %s – the argument is treated as and presented as a string. in your examples, $slug is a string and $this->id is an integer. What does %s mean in …
The STRCMP() function compares two strings. Can we compare strings in SQL? The STRCMP() function compares two strings. How do I match two strings in SQL? In SQL, we can compare two strings using STRCMP () function. STRCMP () returns ‘0’ when the two strings are the same, returns ‘-1’ if the first string is smaller than the second string, …
It can be used to compare two values. If you use double equal sign(==) in MySQL, you will get an error message. Now, compare the above variable value with 10. If both the values are same then the result will be 1 otherwise 0. What does == do in SQL? It can be used to compare two values. If you …