readme.tablefunc

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      CREATE OR REPLACE FUNCTION crosstab_float8_5_cols(IN text,
          OUT row_name TEXT,
          OUT category_1 FLOAT8,
          OUT category_2 FLOAT8,
          OUT category_3 FLOAT8,
          OUT category_4 FLOAT8,
          OUT category_5 FLOAT8)
        RETURNS setof record
        AS '$libdir/tablefunc','crosstab' LANGUAGE C STABLE STRICT;


Example usage

create table ct(id serial, rowclass text, rowid text, attribute text, value text);
insert into ct(rowclass, rowid, attribute, value) values('group1','test1','att1','val1');
insert into ct(rowclass, rowid, attribute, value) values('group1','test1','att2','val2');
insert into ct(rowclass, rowid, attribute, value) values('group1','test1','att3','val3');
insert into ct(rowclass, rowid, attribute, value) values('group1','test1','att4','val4');
insert into ct(rowclass, rowid, attribute, value) values('group1','test2','att1','val5');
insert into ct(rowclass, rowid, attribute, value) values('group1','test2','att2','val6');
insert into ct(rowclass, rowid, attribute, value) values('group1','test2','att3','val7');
insert into ct(rowclass, rowid, attribute, value) values('group1','test2','att4','val8');

SELECT *
FROM crosstab(
  'select rowid, attribute, value
   from ct
   where rowclass = ''group1''
   and (attribute = ''att2'' or attribute = ''att3'') order by 1,2;', 3)
AS ct(row_name text, category_1 text, category_2 text, category_3 text);

 row_name | category_1 | category_2 | category_3
----------+------------+------------+------------
 test1    | val2       | val3       |
 test2    | val6       | val7       |
(2 rows)

==================================================================
Name

crosstab(text, text) - returns a set of row_name, extra, and
                      category value columns

Synopsis

crosstab(text source_sql, text category_sql)

Inputs

  source_sql

    A SQL statement which produces the source set of data. The SQL statement
    must return one row_name column, one category column, and one value
    column. It may also have one or more "extra" columns.

    The row_name column must be first. The category and value columns
    must be the last two columns, in that order. "extra" columns must be
    columns 2 through (N - 2), where N is the total number of columns.

    The "extra" columns are assumed to be the same for all rows with the
    same row_name. The values returned are copied from the first row
    with a given row_name and subsequent values of these columns are ignored
    until row_name changes.

    e.g. source_sql must produce a set something like:
         SELECT row_name, extra_col, cat, value FROM foo;

             row_name    extra_col   cat    value
            ----------+------------+-----+---------
              row1         extra1    cat1    val1
              row1         extra1    cat2    val2
              row1         extra1    cat4    val4
              row2         extra2    cat1    val5
              row2         extra2    cat2    val6
              row2         extra2    cat3    val7
              row2         extra2    cat4    val8

  category_sql

    A SQL statement which produces the distinct set of categories. The SQL
    statement must return one category column only. category_sql must produce
    at least one result row or an error will be generated. category_sql
    must not produce duplicate categories or an error will be generated.

    e.g. SELECT DISTINCT cat FROM foo;

              cat
            -------
              cat1
              cat2
              cat3
              cat4

Outputs

  Returns setof record, which must be defined with a column definition
  in the FROM clause of the SELECT statement, e.g.:

    SELECT * FROM crosstab(source_sql, cat_sql)
    AS ct(row_name text, extra text, cat1 text, cat2 text, cat3 text, cat4 text);

    the example crosstab function produces a set something like:
                      <== values  columns ==>
           row_name   extra   cat1   cat2   cat3   cat4
           ---------+-------+------+------+------+------
             row1     extra1  val1   val2          val4
             row2     extra2  val5   val6   val7   val8

Notes

  1. source_sql must be ordered by row_name (column 1).

  2. The number of values columns is determined at run-time. The 
     column definition provided in the FROM clause must provide for
     the correct number of columns of the proper data types.

  3. Missing values (i.e. not enough adjacent rows of same row_name to
     fill the number of result values columns) are filled in with nulls.

  4. Extra values (i.e. source rows with category not found in category_sql
     result) are skipped.

  5. Rows with a null row_name column are skipped.

  6. You can create predefined functions to avoid having to write out
     the result column names/types in each query.  See the examples
     for crosstab(text).


Example usage

create table cth(id serial, rowid text, rowdt timestamp, attribute text, val text);
insert into cth values(DEFAULT,'test1','01 March 2003','temperature','42');
insert into cth values(DEFAULT,'test1','01 March 2003','test_result','PASS');
insert into cth values(DEFAULT,'test1','01 March 2003','volts','2.6987');
insert into cth values(DEFAULT,'test2','02 March 2003','temperature','53');
insert into cth values(DEFAULT,'test2','02 March 2003','test_result','FAIL');
insert into cth values(DEFAULT,'test2','02 March 2003','test_startdate','01 March 2003');
insert into cth values(DEFAULT,'test2','02 March 2003','volts','3.1234');

SELECT * FROM crosstab
(
  'SELECT rowid, rowdt, attribute, val FROM cth ORDER BY 1',
  'SELECT DISTINCT attribute FROM cth ORDER BY 1'
)
AS
(
       rowid text,
       rowdt timestamp,
       temperature int4,
       test_result text,
       test_startdate timestamp,
       volts float8
);
 rowid |          rowdt           | temperature | test_result |      test_startdate      | volts  
-------+--------------------------+-------------+-------------+--------------------------+--------
 test1 | Sat Mar 01 00:00:00 2003 |          42 | PASS        |                          | 2.6987
 test2 | Sun Mar 02 00:00:00 2003 |          53 | FAIL        | Sat Mar 01 00:00:00 2003 | 3.1234
(2 rows)

==================================================================
Name

connectby(text, text, text[, text], text, text, int[, text]) - returns a set
    representing a hierarchy (tree structure)

Synopsis

connectby(text relname, text keyid_fld, text parent_keyid_fld
            [, text orderby_fld], text start_with, int max_depth
						[, text branch_delim])

Inputs

  relname

    Name of the source relation

  keyid_fld

    Name of the key field

  parent_keyid_fld

    Name of the key_parent field

  orderby_fld

    If optional ordering of siblings is desired:
    Name of the field to order siblings

  start_with

    root value of the tree input as a text value regardless of keyid_fld type

  max_depth

    zero (0) for unlimited depth, otherwise restrict level to this depth

  branch_delim

    If optional branch value is desired, this string is used as the delimiter.
    When not provided, a default value of '~' is used for internal 
    recursion detection only, and no "branch" field is returned.

Outputs

  Returns setof record, which must defined with a column definition
  in the FROM clause of the SELECT statement, e.g.:

    SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0, '~')
      AS t(keyid text, parent_keyid text, level int, branch text);

    - or -

    SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0)
      AS t(keyid text, parent_keyid text, level int);
			
		- or -

    SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'pos', 'row2', 0, '~')
      AS t(keyid text, parent_keyid text, level int, branch text, pos int);

		- or -

    SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'pos', 'row2', 0)
      AS t(keyid text, parent_keyid text, level int, pos int);
    
Notes

  1. keyid and parent_keyid must be the same data type

  2. The column definition *must* include a third column of type INT4 for
     the level value output

  3. If the branch field is not desired, omit both the branch_delim input
     parameter *and* the branch field in the query column definition. Note
     that when branch_delim is not provided, a default value of '~' is used
     for branch_delim for internal recursion detection, even though the branch
     field is not returned.

  4. If the branch field is desired, it must be the fourth column in the query
     column definition, and it must be type TEXT.

  5. The parameters representing table and field names must include double
     quotes if the names are mixed-case or contain special characters.

  6. If sorting of siblings is desired, the orderby_fld input parameter *and*
     a name for the resulting serial field (type INT32) in the query column
     definition must be given.

Example usage

CREATE TABLE connectby_tree(keyid text, parent_keyid text, pos int);

INSERT INTO connectby_tree VALUES('row1',NULL, 0);
INSERT INTO connectby_tree VALUES('row2','row1', 0);
INSERT INTO connectby_tree VALUES('row3','row1', 0);
INSERT INTO connectby_tree VALUES('row4','row2', 1);
INSERT INTO connectby_tree VALUES('row5','row2', 0);
INSERT INTO connectby_tree VALUES('row6','row4', 0);
INSERT INTO connectby_tree VALUES('row7','row3', 0);
INSERT INTO connectby_tree VALUES('row8','row6', 0);
INSERT INTO connectby_tree VALUES('row9','row5', 0);

-- with branch, without orderby_fld
SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0, '~')
 AS t(keyid text, parent_keyid text, level int, branch text);
 keyid | parent_keyid | level |       branch
-------+--------------+-------+---------------------
 row2  |              |     0 | row2
 row4  | row2         |     1 | row2~row4
 row6  | row4         |     2 | row2~row4~row6
 row8  | row6         |     3 | row2~row4~row6~row8
 row5  | row2         |     1 | row2~row5
 row9  | row5         |     2 | row2~row5~row9
(6 rows)

-- without branch, without orderby_fld
SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'row2', 0)
 AS t(keyid text, parent_keyid text, level int);
 keyid | parent_keyid | level
-------+--------------+-------
 row2  |              |     0
 row4  | row2         |     1
 row6  | row4         |     2
 row8  | row6         |     3
 row5  | row2         |     1
 row9  | row5         |     2
(6 rows)

-- with branch, with orderby_fld (notice that row5 comes before row4)
SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'pos', 'row2', 0, '~')
 AS t(keyid text, parent_keyid text, level int, branch text, pos int) ORDER BY t.pos;
 keyid | parent_keyid | level |       branch        | pos 
-------+--------------+-------+---------------------+-----
 row2  |              |     0 | row2                |   1
 row5  | row2         |     1 | row2~row5           |   2
 row9  | row5         |     2 | row2~row5~row9      |   3
 row4  | row2         |     1 | row2~row4           |   4
 row6  | row4         |     2 | row2~row4~row6      |   5
 row8  | row6         |     3 | row2~row4~row6~row8 |   6
(6 rows)

-- without branch, with orderby_fld (notice that row5 comes before row4)
SELECT * FROM connectby('connectby_tree', 'keyid', 'parent_keyid', 'pos', 'row2', 0)
 AS t(keyid text, parent_keyid text, level int, pos int) ORDER BY t.pos;
 keyid | parent_keyid | level | pos
-------+--------------+-------+-----
 row2  |              |     0 |   1
 row5  | row2         |     1 |   2
 row9  | row5         |     2 |   3
 row4  | row2         |     1 |   4
 row6  | row4         |     2 |   5
 row8  | row6         |     3 |   6
(6 rows)

==================================================================
-- Joe Conway