触って動く、検証済みの正解集。

SET STATISTICS PROFILE ON;
SELECT * FROM dbo.tmp_orders WHERE customer_id = 1;
SET STATISTICS PROFILE OFF;

-- ✗ Index効かない
WHERE CONVERT(VARCHAR, created_at, 23)= '2026-05-15'

-- ✓ Index効く
WHERE created_at >= '2026-05-15' AND created_at < '2026-05-16'

-- 全 INDEX の断片化を一発で返す (SAMPLED モード)
SELECT
    OBJECT_NAME(ps.object_id) AS table_name,
    si.name                   AS index_name,
    si.type_desc              AS index_type,

-- 現在のロック保持状況 (Sch-M / Sch-S を含む)
SELECT
    request_session_id      AS session_id,
    resource_type,
    resource_associated_entity_id,

-- 全 INDEX の fill factor 現状
SELECT
    OBJECT_NAME(i.object_id) AS table_name,
    i.name                   AS index_name,
    i.type_desc              AS index_type,

-- 更新多い INDEX を REBUILD + fill factor 85% で再構築
ALTER INDEX [IX_Orders_OrderDate] ON [dbo].[Orders]
REBUILD
WITH (
    FILLFACTOR = 85,

-- これは罠
SELECT * FROM Sessions WHERE SessionId = @sid OPTION (RECOMPILE);
-- ↑ 1秒に100回叩かれる SELECT に付けると、コンパイル時間が積み重なって CPU が爆上がり

SELECT OrderId, CustomerId, TotalAmount
  FROM Orders
 WHERE OrderId = @orderId;

SELECT OrderId, CustomerId, OrderDate
  FROM Orders
 WHERE Status = @status
 OPTION (RECOMPILE);

SELECT SessionId, UserId, LastAccess
  FROM Sessions
 WHERE SessionId = @sid
 OPTION (RECOMPILE);

-- 0.5/1.5/2.5 を四捨五入。リテラル 0.5 は桁が足りず overflow するので CAST で桁を確保
SELECT ROUND(CAST(0.5 AS decimal(2,1)), 0)   -- 1.0
     , ROUND(CAST(1.5 AS decimal(2,1)), 0)   -- 2.0
     , ROUND(CAST(2.5 AS decimal(2,1)), 0);  -- 3.0

-- float は 2.675 を正確に表現できないことがある
SELECT ROUND(CAST(2.675 AS float), 2);          -- 2.67（誤差で 2.675 が 2.6749… 扱い）
-- decimal なら正確
SELECT ROUND(CAST(2.675 AS decimal(10,3)), 2);  -- 2.680（正しく切り上げ）

-- 金額は decimal で。消費税8%を計算
SELECT CAST(1000 AS decimal(12,2)) * 0.08;                         -- 80.0000
-- 表示桁を金額の2桁に揃えるなら、結果も明示的に丸める
SELECT CAST(CAST(1000 AS decimal(12,2)) * 0.08 AS decimal(12,2));  -- 80.00

-- NG: 同点の時に順位がブレる
SELECT customer_id, ROW_NUMBER() OVER (ORDER BY total_sales DESC) AS rn
FROM monthly_sales;

-- OK: customer_id を tiebreaker に

-- 統計情報を見るためのセッション設定
SET STATISTICS IO ON;
SET STATISTICS TIME ON;

-- ROW_NUMBER + 大量データで Sort Operator を確認

SELECT TOP 20
       qs.execution_count,
       qs.total_logical_reads / qs.execution_count AS avg_logical_reads,
       qs.total_elapsed_time / qs.execution_count / 1000 AS avg_elapsed_ms,
       SUBSTRING(qt.text, (qs.statement_start_offset / 2) + 1,

SELECT
    OBJECT_NAME(s.object_id) AS table_name,
    s.name                   AS stats_name,
    STATS_DATE(s.object_id, s.stats_id) AS last_updated,
    s.auto_created,

SELECT
    OBJECT_NAME(si.id) AS table_name,
    si.name            AS index_name,
    si.rowcnt,
    si.rowmodctr,

SET STATISTICS PROFILE ON;
SELECT * FROM Orders WHERE Status = 'エラー' AND OrderDate > '2026-05-01';
SET STATISTICS PROFILE OFF;

-- 今この瞬間メモリ grant を持ってる / 待ってるクエリ
SELECT
    mg.session_id,
    mg.request_time,
    mg.grant_time,

-- Resource Semaphore のキュー俯瞰
SELECT
    resource_semaphore_id,
    target_memory_kb     / 1024 AS target_mb,
    max_target_memory_kb / 1024 AS max_target_mb,

-- 過去 grant が大きかった TOP 10 クエリ (2012 SP3 / 2014 SP2 / 2016+)
SELECT TOP 10
    qs.execution_count,
    qs.max_grant_kb     / 1024 AS max_grant_mb,
    qs.min_grant_kb     / 1024 AS min_grant_mb,

-- tempdb のファイル構成と autogrowth 設定
SELECT
    name,
    physical_name,
    type_desc,

-- products テーブルの category_name を categories マスタの最新名で更新
UPDATE p
SET p.category_name = c.name
FROM products p
INNER JOIN categories c ON p.category_id = c.id

-- 必須プレチェック: 結合元 (categories) に id 重複がないか確認
SELECT id, COUNT(*) AS cnt
FROM categories
GROUP BY id
HAVING COUNT(*) > 1;

-- 各 category_id に複数 categories 行がある場合、name の最新 (MAX(updated_at)) を採用
WITH src AS (
    SELECT
        c.id AS category_id,
        c.name,

-- products に対して、categories マスタの全 id を Upsert
-- (既存 category_id があれば name を更新、なければ INSERT)
MERGE INTO products AS tgt
USING (
    SELECT id, name FROM categories WHERE active = 1

-- (a) 範囲ロックを早めに取る (UPDATE 1 文で完結する場合)
UPDATE T1 WITH (UPDLOCK, HOLDLOCK)
SET status = 'fixed'
FROM T1 INNER JOIN ... ON ...
WHERE ...;

import {Action} from 'redux'



export enum    ActionNames{

   Increment = 'inc',

   Decrement = 'dec'

import {ActionNames, ActionType} from "../Actions/CounterAction";





export interface IState {

   num : number