pgsql_UDF01_jx

1. 需要新建sequence。由于部分表已经有数据，这时，新建的sequence的起始位置不能从1开始。

CREATE OR REPLACE FUNCTION create_sequence(sequence_name character varying, table_name character varying, column_name character varying)
–sequence_name 是需要新建的sequence名称
–table_name 是sequence作用的表
–column_name 是统计当前表的数据量的列值
RETURNS bigint AS
$BODY$
DECLARE
startNum int8;
createsequence “varchar” := ‘’;
selectsequence “varchar” := ‘’;

BEGIN
    --先获取当面表中已经保存了多少数据
    selectsequence := 'select COALESCE(max('||column_name||'), 0) + 1 FROM '|| table_name ||'';
    --将查询出来的结果放入startNum中
execute selectsequence into startNum;
    --声明 创建 sequence的语句。
    createsequence := 'CREATE SEQUENCE '||sequence_name||'
 INCREMENT 1
 MINVALUE 1
 MAXVALUE 9223372036854775807
 START '|| startNum ||' 
 CACHE 1';
--执行创建sequence的SQL语句
execute createsequence;
  
    RETURN startNum;
END;

$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION create_sequence(character varying, character varying, character varying) OWNER TO postgres;

2. 需求，需要将这两行数据 每列相加。
   数据
   2.1 先将将string转换为数组。如1,2,3,4,5转换为 [1,2,3,4,5]
   CREATE OR REPLACE FUNCTION tools_str2array(_originstr text)
   RETURNS integer[] AS
   $BODY$
   declare _cindex INTEGER;
   declare _arrIndex INTEGER;
   DECLARE _arr_str int4[];
   DECLARE _tmp_str VARCHAR(10);
   DECLARE _delimeter VARCHAR(1);
   BEGIN
   _arrIndex:=1;
   _cindex:=1;
   _delimeter:=’,’;

–_strres:=_strres||‘原始字符串是：’||_originStr;

while _cindex<“length”(_originStr) loop
–_strres :=_strres||’【这个是什么？】’||split_part(_originStr, _delimeter, _arrIndex);
_tmp_str:=split_part(_originStr, _delimeter, _arrIndex);
if “character_length”(_tmp_str)<1 then
exit;
end if;
_arr_str:=_arr_str|| CAST(_tmp_str as int4);
_arrIndex:=_arrIndex+1;
END loop;
return _arr_str;
end;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION tools_str2array(text) OWNER TO postgres;

2.2. 新增聚集函数。
CREATE AGGREGATE hot_map_test(
BASETYPE = TEXT,–输入值
SFUNC = csk_test_start,–最初执行的函数
STYPE = TEXT[],–输出类型
FINALFUNC = count_hot_map–最后执行的函数
);

2.3 新建计算函数 计算结果
CREATE AGGREGATE count_test(
BASETYPE = TEXT,
SFUNC = csk_test_start,
STYPE = TEXT[],
FINALFUNC = count_hot_map
);

CREATE OR REPLACE FUNCTION csk_test_start(a text[], s text)
RETURNS text[] AS
$BODY$
BEGIN
RETURN a || s;
END;
$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION csk_test_start(text[], text) OWNER TO postgres;

CREATE OR REPLACE FUNCTION count_hot_map(text[])
RETURNS integer[] AS
$BODY$
DECLARE
startNum int8;
spilt_sql “varchar” := ‘’;
selectsequence “varchar” := ‘’;
temp_array int4[];
result_array int4[];

BEGIN
    for index in 1..array_length($1 , 1) loop
        spilt_sql = 'select tools_str2Array('''||$1[index]||''')';
        execute spilt_sql into temp_array;
         
        for array_items_index in 1..array_length(temp_array, 1) loop
            if result_array[array_items_index] is null then
               result_array[array_items_index] = 0;
            end if;  

            result_array[array_items_index] = result_array[array_items_index] + temp_array[array_items_index];
        end loop;
    end loop;
RETURN result_array;
END;

$BODY$
LANGUAGE plpgsql VOLATILE
COST 100;
ALTER FUNCTION count_hot_map(text[]) OWNER TO postgres;