For IT (database system) students:
In strname string (15) not null, What it mean string (15)?
depending on the language, it probably means that the "strname" string can hold up to 15 characters.
review your language syntax documentation
In st name string (15) not null what it mean string (15)
answer
student
In the context of database systems, the notation "(15)" following the data type declaration for a column indicates the maximum length or size of that column. Specifically, for the "strname" column in your example, it states that the column will store strings with a maximum length of 15 characters.
This is useful because it provides a constraint on the data that can be inserted into the column. Any attempt to insert a string with more than 15 characters would result in an error or truncation of the string to fit within the specified length.
To understand how this works, let's consider an example:
Suppose we have a table called "Student" with the following definition:
CREATE TABLE Student (
studentID INT,
strname VARCHAR(15) NOT NULL
);
In this case, the "strname" column is declared as a VARCHAR data type, which is used to store variable-length strings. The length of the string is specified within parentheses after the VARCHAR keyword, in this case, 15 characters.
The "NOT NULL" constraint ensures that the "strname" column cannot contain a NULL value, meaning it must always have a value assigned to it.
So, if you were to insert a row into the "Student" table like this:
INSERT INTO Student (studentID, strname) VALUES (1, 'John Doe');
This statement would be valid because 'John Doe' has 8 characters, which is within the specified maximum length of 15.
However, if you were to insert a longer string, such as 'Jane Smith-McCarthy', which has 19 characters, for the "strname" column:
INSERT INTO Student (studentID, strname) VALUES (2, 'Jane Smith-McCarthy');
You would either get an error indicating that the string is too long for the column or the string would be automatically truncated to fit within the specified length of 15 characters.
Overall, the "(15)" in the "strname" string declaration represents the maximum length of the string that can be stored in that column of the database table.