в 13:45, 26 мая 2010

2010-05-26T13:45:19Z

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2010-05-26T09:59:08Z

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==Compare a variable length string with a fixed length, and the trailing spaces do matter==



<source lang="sql">

SQL>
SQL> -- Demonstration of string comparison semantics.
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
2 fixed_length_10 CHAR(10);
3 fixed_length_20 CHAR(20);
4 var_length_10 VARCHAR2(10);
5 var_length_20 VARCHAR2(20);
6 BEGIN
7
8 -- Compare a variable length string
9 -- against a fixed length, and the
10 -- trailing spaces do matter.
11 var_length_10 := "Donna";
12 IF fixed_length_10 = var_length_10 THEN
13 DBMS_OUTPUT.PUT_LINE("Char and Varchar2:"
14 || fixed_length_10 ||" = "
15 || var_length_10 );
16 ELSE
17 DBMS_OUTPUT.PUT_LINE("Char and Varchar2: "
18 || fixed_length_10 ||" NOT = "
19 || var_length_10);
20 END IF;
21
22 END;
23 /
Char and Varchar2: NOT = Donna
PL/SQL procedure successfully completed.
SQL>

</source>

==Comparison of a fixed length string and a literal==



<source lang="sql">
SQL>
SQL> -- Demonstration of string comparison.
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
2 fixed_length_10 CHAR(10);
3 fixed_length_20 CHAR(20);
4 var_length_10 VARCHAR2(10);
5 var_length_20 VARCHAR2(20);
6 BEGIN
7
8 --Comparison of a fixed length string and a literal also
9 -- results in the use of blank-padded comparison semantics.
10 IF fixed_length_10 = "Donna" THEN
11 DBMS_OUTPUT.PUT_LINE("Char and constant:" || fixed_length_10 ||" = " || "Donna");
12 ELSE
13 DBMS_OUTPUT.PUT_LINE("Not Donna");
14 END IF;
15 END;
16 /
Not Donna
PL/SQL procedure successfully completed.
SQL>

</source>

==Constants are compared using blank-padded comparison semantics==



<source lang="sql">

SQL>
SQL> -- Demonstration of string comparison.
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
2 fixed_length_10 CHAR(10);
3 fixed_length_20 CHAR(20);
4 var_length_10 VARCHAR2(10);
5 var_length_20 VARCHAR2(20);
6 BEGIN
7 --Constants are compared using blank-padded comparison semantics,
8 -- so the trailing spaces won"t affect the result.
9 IF "Abc" = "Abc " THEN
10 DBMS_OUTPUT.PUT_LINE("Constant: ""Abc"" = ""Abc """);
11 END IF;
12
13 END;
14 /
Constant: "Abc" = "Abc "
PL/SQL procedure successfully completed.
SQL>

</source>

==-Fixed length strings are also compared with blank-padded==



<source lang="sql">

SQL>
SQL> --Demonstration of string comparison semantics.
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
2 fixed_length_10 CHAR(10);
3 fixed_length_20 CHAR(20);
4 BEGIN
5 --Fixed length strings are also compared with blank-padded
6 -- comparison semantic, so the fact that one is longer doesn"t matter.
7 fixed_length_10 := "Donna";
8 fixed_length_20 := "Donna";
9 IF fixed_length_20 = fixed_length_10 THEN
10 DBMS_OUTPUT.PUT_LINE("Char: " || fixed_length_10 || " = " || fixed_length_20);
11 END IF;
12
13 END;
14 /
Char: Donna = Donna
PL/SQL procedure successfully completed.
SQL>

</source>

==The maximum lengths of varchar2 strings do not matter==



<source lang="sql">

SQL>
SQL> -- Demonstration of string comparison semantics.
SQL> SET SERVEROUTPUT ON
SQL> DECLARE
2 fixed_length_10 CHAR(10);
3 fixed_length_20 CHAR(20);
4 var_length_10 VARCHAR2(10);
5 var_length_20 VARCHAR2(20);
6 BEGIN
7 --the maximum lengths of varchar2 strings do not matter,
8 --only the assigned values.
9 var_length_10 := "Donna";
10 var_length_20 := "Donna";
11 IF var_length_20 = var_length_10 THEN
12 DBMS_OUTPUT.PUT_LINE("Both Varchar2:" || var_length_20 ||" = " || var_length_10);
13 ELSE
14 DBMS_OUTPUT.PUT_LINE("Both Varchar2:" || var_length_20 ||" NOT = " || var_length_10);
15 END IF;
16 END;
17 /
Both Varchar2:Donna = Donna
PL/SQL procedure successfully completed.
SQL>

</source>

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в 13:45, 26 мая 2010

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