?? ?? ?? ?? ? ??
PostgreSQL??? ??? ?? ??? ?? ?? ?? ?? ???? ? ?? ??? ? ????. ? ??? ???? ?.
? ???? RANGE ??(Postgres 11 ?? ??)
Postgres 11 ??? ?? RANGE ??? ???? PRECEDING ? EXCLUDE ??? ???? ?? ??? ??? ? ????.
SELECT id, ts , count(*) OVER (ORDER BY ts RANGE '1 hour' PRECEDING EXCLUDE CURRENT ROW) FROM test ORDER BY ts;
?? PostgreSQL ??
?? ??? PostgreSQL? ?? ?? ?? ??? ??? ????. ?? ??:
Roman's Query(ROM)
SELECT id, ts , (SELECT count(*)::int - 1 FROM unnest(dates) x WHERE x >= sub.ts - interval '1h') AS ct FROM ( SELECT id, ts , array_agg(ts) OVER (ORDER BY ts) AS dates FROM test ) sub;
?? ??(ARR)
SELECT id, ts , (SELECT count(*) FROM test t1 WHERE t1.ts >= t.ts - interval '1h' AND t1.ts < t.ts) AS ct FROM test t ORDER BY ts;
PL/pgSQL ?? (FNC)
CREATE OR REPLACE FUNCTION running_window_ct(_intv interval = '1 hour') RETURNS TABLE (id bigint, ts timestamp, ct int) AS $func$ DECLARE cur CURSOR FOR SELECT t.ts + _intv AS ts1 , row_number() OVER (ORDER BY t.ts ROWS UNBOUNDED PRECEDING) AS rn FROM test t ORDER BY t.ts; rec record; rn int; BEGIN OPEN cur; FETCH cur INTO rec; ct := -1; FOR id, ts, rn IN SELECT t.id, t.ts, row_number() OVER (ORDER BY t.ts ROWS UNBOUNDED PRECEDING) FROM test t ORDER BY t.ts LOOP IF rec.ts1 >= ts THEN ct := ct + 1; ELSE LOOP FETCH cur INTO rec; EXIT WHEN rec.ts1 >= ts; END LOOP; ct := rn - rec.rn; END IF; RETURN NEXT; END LOOP; END $func$;
??? ?? ???? ?? ??:
SELECT * FROM running_window_ct('1 hour');
? ??? PostgreSQL?? ?? ?? ??? ?? ?? ???? ??? ??????? ?? ?????. ??? ??? PHP ??? ????? ?? ?? ??? ?????!

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TOSECIBERYNECTTOEREMOTEMYSQLSERVER, USESSHTUNNENG, CONFIGUREMYSQLFORREMOTEACCESS, SETFIREWALLRULES ? CONSIDERSSLENCRYPTION .First, SpectionANSSHTUNNELWITHSSH-L3307 : LocalHost : 3306user@remote-Server-NandConnectViamySQL-H127.0.1-P3307.second, editmys

MySQL? ? ????? ??? ??? ????? ?? ?? ??? ?? ???????. 1. Windows ??? : MySQL ?? ?????? ? ??? ????? (?? ??? ????? C : \ programfiles \ mysql \ mysqlserverx.x \ bin), "? ???"→ "??"→ "Advanced System ??"→ "?? ??", "??? ??", MySQlb in wors in mysqlb in wors in mysqlb in world in that the the the the the seel worl ?? ????? ?? ???? MySQL? ??????-Version Versification; 2.Macos ? Linux ??? : Bash ??? ?? ~/.bashrc ?? ~/.bash_

MySQL? ?? ???? ?? ??? ??? ? A??, ?? MVCC ? GAP ?? ??? ?? ??? ?? ? ?? ???? ??? ???? ???? ?? ?? ??? ????. ?? ?? ??? ??? ?? (??)? ????? ??? ??? ????? ?? ?? ??? ????? 1. ??? ??? (read committed)? ?? ? ???? ?? ? ??? ?? ? ??? ?? ? ?? ?? ?? ?? ? ? ????. ???, ??? ??? ????? ??? ??;

mysqlworkbench? ??? ?? ??? ?? ??? ?????. ?? ??? ?? ??? ?? ????. 1. Windows ???? %appdata %\ mysql \ workbench \ connections.xml? ????. 2. MacOS ???? ~/Library/ApplicationSupport/MySQL/Workbench/Connections.xml? ????. 3. ????? Linux ???? ~/.mysql/workbench/connections.xml ?? ~/.local/share/data/mysql/wor? ????.

MySQL ??? ?? ??? ?? ?? ??? ?? ??? ??????. 1. ?? ?? ?? ?? ???? Slow_Query_Log ? Long_Query_Time; 2. ???? ??? ?? ??? ???? ? ????? query_time, lock_time, rows_examined? ?? ?? ??? ???? ????. 3. ??? ????? ???? ?? mysqldumpslow ?? pt-query idigest ??? ??????. 4. ??? ???? ??? ??, ??*???*, ??? ?? ?? ?? ?????. ?? ??, user_id? ???? ???? ?? ? ?? ?? ?? ??? ?? ???? ???? ? ????.

MySQLDump? MySQL ??????? ??? ??? ???? ???? ?????. ??????? ???? ?? ?? ? ?? ?? ???? SQL ??? ?????. 1. ?? ??? ????? ??? ?????? ??? ???? ??? SQL ???? ?????. 2. ??? ?????? ?? ??? ??? ???? TB ?? ???? ?? ???? ???? ????. 3. ???? ???-single transaction,-databases,-all-databases,-routines ?; 4. MySQL ??? ???? ?? ?? ?? ?? ?? ? ??? ?? ??? ???? ? ????. 5. ??? ????? ????? ?? ? ?? ??? ???? ?? ????.

MySQL?? NULL ?? ?? ? ? 1. ???? ?? ? ? ? ??? NotNull? ???? ?? ??? NULL? ?????. 2. iSnull ?? ISNOTNULL = ??! =; 3. Ifnull ?? Coalesce ??? ????? ???? ???? ? ??? ? ????. 4. ?? ?? ????? NULL ?? ?? ??? ?? ???? ??? ?? ? ORM ??? ?? ?? ?????? ??????. NULL? ???? ?? ?? ???? ??? ???? ?? ?? ?? ????. ??? ???? ??, ?? ? ???? ?? ? ??? ?? ??? ??? ?? ???????. ??? ??? ???? ??? ?? ?? ??? ????? ?? ? ????.

MySQL? ?? ????? ?????? ?? ??? ?????. 1. MySQL ?? ??, sudosystemctlstopmysql ?? sudosystemctlstopmysqld? ??????. 2. -skip-grant-tables ???? mysql? ???? sudomysqld-skip-grant-tables &; 3. MySQL? ????? ?? SQL ??? ???? FlushPrivileges; Alteruser'Root '@'localHost'IndifiedBy'Your_new? ?? ??? ?? ????? ??????.
