一、在使用 date_format、from_unixtime、to_days、yearweek 函數時，Gbase 8s 數據庫不支持，可以使用創建 UDR 外部函數來實現

二、登錄命令控制臺或者使用 navicat 連接 Gbase 數據庫

這里使用 navicat ，點擊新增連接選擇 PostGreSql 驅動，添加地址、賬號、密碼
連接數據庫后，選中目標庫選中目標模式，再點擊函數-新增函數執行以下語句即可

注意：這里 選中 public 模式，使用 mss 用戶，自行修改函數中對應的內容（ 例如：FUNCTION “public”.“date_format”、OWNER TO “mss”）

1. date_format 函數

   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') thenSELECT to_char(smalldatetime_to_timestamp($1),'YYYY') into result_current_date;when upper('%Y-%M') thenSELECT to_char(smalldatetime_to_timestamp($1),'YYYY-MM') into result_current_date;                    when upper('%Y-%M-%D') thenSELECT to_char(smalldatetime_to_timestamp($1),'YYYY-MM-DD') into result_current_date;when upper('%Y-%M-%D %h') thenSELECT to_char(smalldatetime_to_timestamp($1),'YYYY-MM-DD HH24') into result_current_date;when upper('%Y-%M-%D %h:%m') thenSELECT to_char(smalldatetime_to_timestamp($1),'YYYY-MM-DD HH24:MI') into result_current_date;when upper('%Y-%M-%D %h:%m:%s') thenSELECT to_char(smalldatetime_to_timestamp($1),'YYYY-MM-DD HH24:MI:ss') into result_current_date;            when upper('%M') thenSELECT to_char(smalldatetime_to_timestamp($1),'MM') into result_current_date;                when upper('%M-%D') thenSELECT to_char(smalldatetime_to_timestamp($1),'MM-DD') into result_current_date;when upper('%D') thenSELECT to_char(smalldatetime_to_timestamp($1),'DD') into result_current_date;when upper('%h') thenSELECT to_char(smalldatetime_to_timestamp($1),'HH24') into result_current_date;    when upper('%h:%m') thenSELECT to_char(smalldatetime_to_timestamp($1),'HH24:MI') into result_current_date;            when upper('%m') thenSELECT to_char(smalldatetime_to_timestamp($1),'MI') into result_current_date;                            when upper('%m:%s') thenSELECT to_char(smalldatetime_to_timestamp($1),'MI:ss') into result_current_date;        when upper('%s') thenSELECT to_char(smalldatetime_to_timestamp($1),'ss') into result_current_date;                                                                when upper('%h:%m:%s') thenSELECT to_char(smalldatetime_to_timestamp($1),'HH24:MI:ss') into result_current_date;            elseSELECT to_char(smalldatetime_to_timestamp($1),informate) into result_current_date;end case;RETURN result_current_date;
   END$BODY$LANGUAGE plpgsql VOLATILECOST 100;ALTER FUNCTION "public"."date_format"("ctimestamp" timestamptz, "informate" varchar) OWNER TO "mss";
   

   查詢語句：

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

2. from_unixtime 函數

   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 VOLATILECOST 100;ALTER FUNCTION "public"."from_unixtime"("t" int8) OWNER TO "mss";
   

   查詢語句：

   select from_unixtime(1692328679);
   

3. to_days 函數

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

   查詢語句：

   select to_days(now());
   

4. yearweek 函數

   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;BEGINSELECT 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 VOLATILECOST 100;ALTER FUNCTION "public"."yearweek"("ctimestamp" timestamptz) OWNER TO "mss";
   

   查詢語句：

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