南大通用数据库(Gbase 8s) 创建UDR外部函数

一、在使用 date_format、from_unixtime、to_days、yearweek 函数时，Gbase 8s 数据库不支持，可以使用创建 UDR 外部函数来实现

二、登录命令控制台或者使用 navicat 连接 Gbase 数据库

这里使用 navicat ，点击新增连接选择 PostGreSql 驱动，添加地址、账号、密码

连接数据库后，选中目标库选中目标模式，再点击函数-新增函数执行以下语句即可

注意：这里 选中 public 模式，使用 mss 用户，自行修改函数中对应的内容（ 例如：FUNCTION "public"."date_format"、OWNER TO "mss"）

1. date_format 函数

   CREATE OR REPLACE FUNCTION "public"."date_format"("ctimestamp" timestamptz, "informate" varchar)
    RETURNS "pg_catalog"."varchar" AS $BODY$
      -- Routine body goes here...
    DECLARE  
          result_current_date varchar;
      BEGIN
   --             IF upper($1) = upper('YYYY-MM-DD') || upper($1) = upper('%Y-%M-%D') THEN
   --                     SELECT to_char(now(),'YYYY-MM-DD') into result_current_date;
   --             END IF;
   --     
   --             
   --             IF upper($1) = upper('%Y-%M-%D %h:%m') || upper($1) = upper('%Y-%M-%D %h:%m') THEN
   --                     SELECT to_char(now(),'YYYY-MM-DD HH:mm') into result_current_date;
   --             END IF;
   --             
   --           IF upper($1) = upper('%Y-%M-%D %h:%m:%s') || upper($1) = upper('%Y-%M-%D %h:%m:%s') THEN
   --                     SELECT to_char(now(),'YYYY-MM-DD HH:mm:ss') into result_current_date;
   --             END IF;
              
              case upper($2)
                  when upper('%Y') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'YYYY') into result_current_date;
                  when upper('%Y-%M') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'YYYY-MM') into result_current_date;                    
                  when upper('%Y-%M-%D') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'YYYY-MM-DD') into result_current_date;
                  when upper('%Y-%M-%D %h') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'YYYY-MM-DD HH24') into result_current_date;
                  when upper('%Y-%M-%D %h:%m') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'YYYY-MM-DD HH24:MI') into result_current_date;
                  when upper('%Y-%M-%D %h:%m:%s') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'YYYY-MM-DD HH24:MI:ss') into result_current_date;            
                  when upper('%M') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'MM') into result_current_date;                
                  when upper('%M-%D') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'MM-DD') into result_current_date;
                  when upper('%D') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'DD') into result_current_date;
                  when upper('%h') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'HH24') into result_current_date;    
                  when upper('%h:%m') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'HH24:MI') into result_current_date;            
                  when upper('%m') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'MI') into result_current_date;                            
                  when upper('%m:%s') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'MI:ss') into result_current_date;        
                  when upper('%s') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'ss') into result_current_date;                                                                
                  when upper('%h:%m:%s') then
                      SELECT to_char(smalldatetime_to_timestamp($1),'HH24:MI:ss') into result_current_date;            
                                                  
                  else
                      SELECT to_char(smalldatetime_to_timestamp($1),informate) into result_current_date;
              end case;
              
          RETURN result_current_date;
   END$BODY$
    LANGUAGE plpgsql VOLATILE
    COST 100;
   
   ALTER FUNCTION "public"."date_format"("ctimestamp" timestamptz, "informate" varchar) OWNER TO "mss";

   查询语句：

   SELECT date_format(now(),'%Y-%M-%D %h:%m:%s');

2. from_unixtime 函数

   CREATE OR REPLACE FUNCTION "public"."from_unixtime"("t" int8)
     RETURNS "pg_catalog"."timestamp" AS $BODY$
     DECLARE  
           result_current_date timestamp;
     BEGIN  
        select TO_TIMESTAMP(t) into result_current_date;
       RETURN result_current_date;
   END; $BODY$
     LANGUAGE plpgsql VOLATILE
     COST 100;
     
   ALTER FUNCTION "public"."from_unixtime"("t" int8) OWNER TO "mss";

   查询语句：

   select from_unixtime(1692328679);

3. to_days 函数

   -- 参数 varchar类型
   CREATE OR REPLACE FUNCTION "public"."to_days"("ctimestamp" varchar)
     RETURNS "pg_catalog"."int4" AS $BODY$
       -- Routine body goes here...
     DECLARE  
           result_current_date int4;
       BEGIN
               SELECT TIMESTAMPDIFF(day, '0001-01-01', $1) into result_current_date;
           RETURN result_current_date;
   END$BODY$
     LANGUAGE plpgsql VOLATILE
     COST 100;
   
   
   ALTER FUNCTION "public"."to_days"("ctimestamp" varchar) OWNER TO "mss";
   
   -- 参数 timestamptz 类型
   CREATE OR REPLACE FUNCTION "public"."to_days"("ctimestamp" timestamptz)
     RETURNS "pg_catalog"."int4" AS $BODY$
       -- Routine body goes here...
     DECLARE  
           result_current_date int4;
       BEGIN
               SELECT TIMESTAMPDIFF(day, '0001-01-01', $1) into result_current_date;
           RETURN result_current_date;
   END$BODY$
     LANGUAGE plpgsql VOLATILE
     COST 100;
   
   
   ALTER FUNCTION "public"."to_days"("ctimestamp" timestamptz) OWNER TO "mss";

   查询语句：

   select to_days(now());

4. yearweek 函数

   CREATE OR REPLACE FUNCTION "public"."yearweek"("ctimestamp" timestamptz)
     RETURNS "pg_catalog"."int4" AS $BODY$
       -- Routine body goes here...
     DECLARE  
           week_n int4;
           year_n int4;
       BEGIN
               SELECT to_char(smalldatetime_to_timestamp($1),'YYYY') into year_n;
               SELECT trunc(1 + (smalldatetime_to_timestamp($1) - TRUNC(smalldatetime_to_timestamp($1), 'YEAR')) / 7) into week_n;
           RETURN ((year_n*100)+week_n);
   END$BODY$
     LANGUAGE plpgsql VOLATILE
     COST 100;
   
   
   ALTER FUNCTION "public"."yearweek"("ctimestamp" timestamptz) OWNER TO "mss";

   查询语句：

   select YEARWEEK(now());
   select YEARWEEK('2023-01-03 12');