Oracle PL/SQL Tutorial/Numerical Math Functions/TRUNC — различия между версиями

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Текущая версия на 10:08, 26 мая 2010

The second argument of TRUNC defaults to 0

SQL> -- create demo table
SQL> create table myTable(
  2    id           NUMBER(2),
  3    value        NUMBER(6,2)
  4  )
  5  /
Table created.
SQL>
SQL> -- prepare data
SQL> insert into myTable(ID,  value)values (1,9)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (2,2.11)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (3,3.44)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (4,-4.21)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (5,10)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (6,3)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (7,-5.88)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (8,123.45)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (9,98.23)
  2  /
1 row created.
SQL>
SQL> select * from myTable
  2  /
        ID      VALUE
---------- ----------
         1          9
         2       2.11
         3       3.44
         4      -4.21
         5         10
         6          3
         7      -5.88
         8     123.45
         9      98.23
9 rows selected.
SQL>
SQL> SELECT id, value, TRUNC(value,0), TRUNC(value) FROM myTable
  2  /
        ID      VALUE TRUNC(VALUE,0) TRUNC(VALUE)
---------- ---------- -------------- ------------
         1          9              9            9
         2       2.11              2            2
         3       3.44              3            3
         4      -4.21             -4           -4
         5         10             10           10
         6          3              3            3
         7      -5.88             -5           -5
         8     123.45            123          123
         9      98.23             98           98
9 rows selected.
SQL>
SQL>
SQL>
SQL> -- clean the table
SQL> drop table myTable
  2  /
Table dropped.
SQL>


The second argument of TRUNC, precision, may be negative, which means displacement to the left of the decimal point

SQL>
SQL> -- create demo table
SQL> create table myTable(
  2    id           NUMBER(2),
  3    value        NUMBER(6,2)
  4  )
  5  /
Table created.
SQL>
SQL> -- prepare data
SQL> insert into myTable(ID,  value)values (1,9)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (2,2.11)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (3,3.44)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (4,-4.21)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (5,10)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (6,3)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (7,-5.88)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (8,123.45)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (9,98.23)
  2  /
1 row created.
SQL>
SQL> select * from myTable
  2  /
        ID      VALUE
---------- ----------
         1          9
         2       2.11
         3       3.44
         4      -4.21
         5         10
         6          3
         7      -5.88
         8     123.45
         9      98.23
9 rows selected.
SQL>
SQL>
SQL> SELECT id, value, TRUNC(value,-1) FROM myTable
  2  /
        ID      VALUE TRUNC(VALUE,-1)
---------- ---------- ---------------
         1          9               0
         2       2.11               0
         3       3.44               0
         4      -4.21               0
         5         10              10
         6          3               0
         7      -5.88               0
         8     123.45             120
         9      98.23              90
9 rows selected.
SQL>
SQL>
SQL> -- clean the table
SQL> drop table myTable
  2  /
Table dropped.
SQL>


TRUNC(5.75)

SQL> select TRUNC(5.75) from dual;
TRUNC(5.75)
-----------
          5


TRUNC(

SQL> select TRUNC(5.75, 1) from dual;
TRUNC(5.75,1)
-------------
          5.7


TRUNC(5.75, -1) (2)

SQL> select TRUNC(5.75, -1) from dual;
TRUNC(5.75,-1)
--------------
             0


TRUNC column value

SQL>
SQL>
SQL> -- create demo table
SQL> create table myTable(
  2    id           NUMBER(2),
  3    value        NUMBER(6,2)
  4  )
  5  /
Table created.
SQL>
SQL> -- prepare data
SQL> insert into myTable(ID,  value)values (1,9)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (2,2.11)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (3,3.44)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (4,-4.21)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (5,10)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (6,3)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (7,-5.88)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (8,123.45)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (9,98.23)
  2  /
1 row created.
SQL>
SQL> select * from myTable
  2  /
        ID      VALUE
---------- ----------
         1          9
         2       2.11
         3       3.44
         4      -4.21
         5         10
         6          3
         7      -5.88
         8     123.45
         9      98.23
9 rows selected.
SQL>
SQL> SELECT id, value,TRUNC(value) FROM myTable
  2  /
        ID      VALUE TRUNC(VALUE)
---------- ---------- ------------
         1          9            9
         2       2.11            2
         3       3.44            3
         4      -4.21           -4
         5         10           10
         6          3            3
         7      -5.88           -5
         8     123.45          123
         9      98.23           98
9 rows selected.
SQL>
SQL>
SQL> -- clean the table
SQL> drop table myTable
  2  /
Table dropped.
SQL>
SQL>


TRUNC may have a second argument to handle precision: means the distance to the right of the decimal point

SQL> -- create demo table
SQL> create table myTable(
  2    id           NUMBER(2),
  3    value        NUMBER(6,2)
  4  )
  5  /
Table created.
SQL>
SQL> -- prepare data
SQL> insert into myTable(ID,  value)values (1,9)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (2,2.11)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (3,3.44)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (4,-4.21)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (5,10)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (6,3)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (7,-5.88)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (8,123.45)
  2  /
1 row created.
SQL> insert into myTable(ID,  value)values (9,98.23)
  2  /
1 row created.
SQL>
SQL> select * from myTable
  2  /
        ID      VALUE
---------- ----------
         1          9
         2       2.11
         3       3.44
         4      -4.21
         5         10
         6          3
         7      -5.88
         8     123.45
         9      98.23
9 rows selected.
SQL>
SQL>
SQL> SELECT id, value, TRUNC(value,1) FROM myTable
  2  /
        ID      VALUE TRUNC(VALUE,1)
---------- ---------- --------------
         1          9              9
         2       2.11            2.1
         3       3.44            3.4
         4      -4.21           -4.2
         5         10             10
         6          3              3
         7      -5.88           -5.8
         8     123.45          123.4
         9      98.23           98.2
9 rows selected.
SQL>
SQL>
SQL> -- clean the table
SQL> drop table myTable
  2  /
Table dropped.
SQL>


TRUNC(x, [y]) gets the result of truncating the number x to an optional y decimal places.

If y is omitted, x is truncated to zero decimal places.

If y is negative, x is truncated to the left of the decimal point.

The following example displays truncating 5.75 to zero, 1, and - 1 decimal places:



SQL> SELECT TRUNC(5.75), TRUNC(5.75, 1), TRUNC(5.75, -1) FROM dual;
TRUNC(5.75) TRUNC(5.75,1) TRUNC(5.75,-1)
----------- ------------- --------------
          5           5.7              0
SQL>