I am stuying PL/SQL & I am going through the bind variable . I understood that the bind variable we used to pass RUN-TIME values.
but what is the difference between & and :(colon) in PL/SQL? both are same or is their any difference between this two? when should I use & and : ?
The &
is used in SQL*Plus
only, it has no meaning outside of it.
While SQL*Plus
"parses" the input buffer, it replaces &variables
with what they were define
d to. See also this link and this link . The technical term is substitution variable .
On the other hand :variable
are real bind variables. They are used when Oracle's SQL engine "parses" and executes the SQL statement. See for example this link or this link .
So, in short, &variables
are replaced by SQL*Plus and then passed to Oracle's SQL engine, while :variables
are left untouched by SQL Plus and passed to Oracle's SQL engine as they appear. Outside fo SQL Plus, &
makes no sense.
&
has no meaning in PL/SQL, it is actually a SQL Plus feature (that has been copied in Toad, SQL Developer etc. for compatibility). In SQL Plus, &
is used to define a substitution variable , which is replaced with specified replacement text by SQL Plus before the code is sent to the server to be processed.
The correct syntax for a SQL Plus substitution variable is &name.
ie is begins with a &
and ends with a .
, but in most situations the .
is optional. So when you run this code in SQL Plus:
select * from emp where ename = '&name.';
SQL Plus prompts the user for a value for name
and substitues this into the query before it is run. So if the user enters KING
then the SQL actually run is:
select * from emp where ename = 'KING';
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