SQL: SELECT Command ~ JAVA INTERVIEW QUESTIONS

SQL: SELECT Command

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SELECT command is use in SQL to "SELECT [some info] FROM [a location]". Now, this is the basic structure of the SELECT query, where SELECT and FROM are 2 commands of SQL. Here, [some info] part will be the column names separated by comma (,) sign and [a location] part will be the name of the Table or View. So, the syntax will be :

For Single Column :
Syntax : SELECT [Column_name] FROM [Table_Name];

For Multiple Columns :
Syntax : SELECT [Column1_name, Column2_name, Column3_name] FROM [Table_Name];

Now, what if you want to select all the columns of a table or a view. Do you have to write all the column name for that. No necessarily, you can user the star (*) sign in [Column_name] area. Then the syntax will be:

For All Columns :
Syntax : SELECT * FROM [Table_Name];

Example:
Suppose there is a table to keep
Employee Details (Table Name: employee_details), which contains
Employee ID(Column Name: emp_id),
Employee Name(Column Name: emp_name),
Employee Address:(Column Name: emp_address) and
Employee Role: (Column Name: emp_role).

Table: employee_details

Now, to select emp_id and emp_name from the table, the query will be,

SELECT emp_id, emp_name FROM employee_details;

Result:

Again, if you wants to select all the colunms' record, then the query will be,

SELECT * FROM employee_details;

Result:

1 Responses to “ SQL: SELECT Command ”

Power Cords said... 21 February 2013 at 13:56 Good to see the SQL learning in this blog. SQL is easy command base language but difficult to learn for so many people specially for new web programmers.