Mysql替换为瀚高数据库部分函数转换V4.5版本

Mysql替换为瀚高数据库，部分语法和函数不兼容，整理了部分替换，（注意要在对应的模式下执行）例如：

1、find_in_set函数

sql 复制代码

create or replace function find_in_set(bigint, varchar)  
returns boolean as
$$ declare list text[];
len bigint; 
begin
if $2 ='' then 
return 0;
end if; 
list := pg_catalog.string_to_array($2::text, ','); 
len := pg_catalog.array_upper(list, 1); 
for i in 1..len loop 
if list[i] = $1::text 
then
if i>0 then 
return true;
else 
return false; end if;
end if; 
end loop; 
return 0; 
end; 
$$ language plpgsql ;

2、错误：操作符不存在：bigint=character varying

sql 复制代码

create cast(varchar as bigint) with inout as IMPLICIT；

3、错误：函数curdate()不存在

sql 复制代码

CREATE OR REPLACE FUNCTION curdate()
RETURNS date AS $$
SELECT CURRENT_DATE::date;
$$ LANGUAGE sql IMMUTABLE;

4、错误：函数to_days(timestamp with time zone)不存在

sql 复制代码

 CREATE OR REPLACE FUNCTION to_days(timestamp with time zone)
RETURNS INTEGER AS $$
SELECT ($1 AT TIME ZONE 'UTC')::date - '0001-01-01 BC'::date;
$$ IMMUTABLE STRICT LANGUAGE SQL;

5、错误：函数date_format(timestamp with time zone,unknown)不存在

sql 复制代码

CREATE OR REPLACE FUNCTION DATE_FORMAT(
    date_str timestamptz,
    format_str text
) RETURNS varchar AS $$
DECLARE
    ts timestamptz;
    pg_format text;
BEGIN
    IF date_str IS NULL OR format_str IS NULL THEN
        RETURN NULL;
    END IF;

    BEGIN
        ts := date_str;
    EXCEPTION WHEN OTHERS THEN
        RETURN NULL;
    END;

    pg_format := format_str;
    pg_format := replace(pg_format, '%Y', 'YYYY');
    pg_format := replace(pg_format, '%y', 'YY');
    pg_format := replace(pg_format, '%m', 'MM');
    pg_format := replace(pg_format, '%c', 'MM');
    pg_format := replace(pg_format, '%M', 'Month');
    pg_format := replace(pg_format, '%b', 'Mon');
    pg_format := replace(pg_format, '%d', 'DD');
    pg_format := replace(pg_format, '%e', 'D');
    pg_format := replace(pg_format, '%H', 'HH24');
    pg_format := replace(pg_format, '%h', 'HH12');
    pg_format := replace(pg_format, '%k', 'HH24');
    pg_format := replace(pg_format, '%I', 'HH12');
    pg_format := replace(pg_format, '%i', 'MI');
    pg_format := replace(pg_format, '%s', 'SS');
    pg_format := replace(pg_format, '%p', 'AM');
    pg_format := replace(pg_format, '%W', 'Day');
    pg_format := replace(pg_format, '%a', 'Dy');
    pg_format := replace(pg_format, '%T', 'HH24:MI:SS');
    pg_format := replace(pg_format, '%r', 'HH12:MI:SS AM');
    pg_format := replace(pg_format, '%f', 'US');

    RETURN to_char(ts, pg_format);
END;
$$ LANGUAGE plpgsql IMMUTABLE;

6、函数date_format(character varying,unknown)不存在

sql 复制代码

CREATE OR REPLACE FUNCTION date_format(
    in_date varchar, 
    format_str text  
) RETURNS varchar AS $$
DECLARE
    ts timestamptz; 
BEGIN
    IF in_date IS NULL OR format_str IS NULL THEN
        RETURN NULL;
    END IF;
    BEGIN
        ts := in_date::timestamptz;
    EXCEPTION WHEN OTHERS THEN
        RETURN NULL;
    END;
    RETURN DATE_FORMAT(ts, format_str);
END;
$$ LANGUAGE plpgsql IMMUTABLE;

7、函数ifnull(character varying,unknown)不存在

sql 复制代码

CREATE OR REPLACE FUNCTION ifnull(anyelement, anyelement)
RETURNS anyelement AS $$
BEGIN
    RETURN COALESCE($1, $2);
END;
$$ LANGUAGE plpgsql IMMUTABLE;

CREATE OR REPLACE FUNCTION ifnull(anyelement, text)
RETURNS anyelement AS $$
BEGIN
    RETURN COALESCE($1, $2::anyelement);
END;
$$ LANGUAGE plpgsql IMMUTABLE;

8、函数date_add(character varying,interval)不存在

sql 复制代码

CREATE OR REPLACE FUNCTION date_add(
    start_dt varchar,  
    intv interval    
) RETURNS timestamp AS $$
BEGIN
    RETURN date_add(start_dt::timestamp with time zone,intv);
END;
$$ LANGUAGE plpgsql;

注意：上述这些只需要在瀚高数据库建立相应的函数就可以，不需要改变Mysql的语法。建立之后之前的语法也会被适用