Back to Details

sqlserver-expert

Compare original and translation side by side

🇺🇸

Original

English
🇨🇳

Translation

Chinese

SQL Server Expert

SQL Server 专家

You are a DBA and developer expert in Microsoft SQL Server.
您是一位精通Microsoft SQL Server的数据库管理员（DBA）和开发人员。

T-SQL Advanced

T-SQL 进阶技巧

CTEs (Common Table Expressions)

CTE（通用表表达式）

sql
WITH RankedUsers AS (
  SELECT
    Id, Name, Email,
    ROW_NUMBER() OVER (PARTITION BY Department ORDER BY HireDate) AS RowNum
  FROM Users
)
SELECT * FROM RankedUsers WHERE RowNum = 1;
sql
WITH RankedUsers AS (
  SELECT
    Id, Name, Email,
    ROW_NUMBER() OVER (PARTITION BY Department ORDER BY HireDate) AS RowNum
  FROM Users
)
SELECT * FROM RankedUsers WHERE RowNum = 1;

Window Functions

窗口函数

sql
SELECT
  OrderId,
  OrderDate,
  Amount,
  SUM(Amount) OVER (ORDER BY OrderDate) AS RunningTotal,
  LAG(Amount) OVER (ORDER BY OrderDate) AS PreviousAmount,
  AVG(Amount) OVER (PARTITION BY CustomerId) AS CustomerAvg
FROM Orders;
sql
SELECT
  OrderId,
  OrderDate,
  Amount,
  SUM(Amount) OVER (ORDER BY OrderDate) AS RunningTotal,
  LAG(Amount) OVER (ORDER BY OrderDate) AS PreviousAmount,
  AVG(Amount) OVER (PARTITION BY CustomerId) AS CustomerAvg
FROM Orders;

MERGE Statement

MERGE 语句

sql
MERGE INTO TargetTable AS target
USING SourceTable AS source
ON target.Id = source.Id
WHEN MATCHED THEN
  UPDATE SET target.Name = source.Name
WHEN NOT MATCHED THEN
  INSERT (Id, Name) VALUES (source.Id, source.Name)
WHEN NOT MATCHED BY SOURCE THEN
  DELETE;
sql
MERGE INTO TargetTable AS target
USING SourceTable AS source
ON target.Id = source.Id
WHEN MATCHED THEN
  UPDATE SET target.Name = source.Name
WHEN NOT MATCHED THEN
  INSERT (Id, Name) VALUES (source.Id, source.Name)
WHEN NOT MATCHED BY SOURCE THEN
  DELETE;

Node.js Integration (mssql)

Node.js 集成（基于mssql）

Connection Pool

连接池

typescript
import sql from "mssql";

const config: sql.config = {
  user: process.env.SQL_USER,
  password: process.env.SQL_PASSWORD,
  server: process.env.SQL_SERVER || "localhost",
  database: process.env.SQL_DATABASE,
  options: {
    encrypt: true,
    trustServerCertificate: true,
    enableArithAbort: true,
  },
  pool: {
    min: 2,
    max: 10,
    idleTimeoutMillis: 30000,
  },
};

let pool: sql.ConnectionPool | null = null;

export async function getPool(): Promise<sql.ConnectionPool> {
  if (!pool) {
    pool = await sql.connect(config);
  }
  return pool;
}
typescript
import sql from "mssql";

const config: sql.config = {
  user: process.env.SQL_USER,
  password: process.env.SQL_PASSWORD,
  server: process.env.SQL_SERVER || "localhost",
  database: process.env.SQL_DATABASE,
  options: {
    encrypt: true,
    trustServerCertificate: true,
    enableArithAbort: true,
  },
  pool: {
    min: 2,
    max: 10,
    idleTimeoutMillis: 30000,
  },
};

let pool: sql.ConnectionPool | null = null;

export async function getPool(): Promise<sql.ConnectionPool> {
  if (!pool) {
    pool = await sql.connect(config);
  }
  return pool;
}

Parameterized Queries

参数化查询

typescript
const pool = await getPool();
const request = pool.request();

request.input("userId", sql.Int, userId);
request.input("status", sql.VarChar(50), status);

const result = await request.query(`
  SELECT * FROM Users
  WHERE Id = @userId AND Status = @status
`);
typescript
const pool = await getPool();
const request = pool.request();

request.input("userId", sql.Int, userId);
request.input("status", sql.VarChar(50), status);

const result = await request.query(`
  SELECT * FROM Users
  WHERE Id = @userId AND Status = @status
`);

Useful Queries

实用查询语句

List Tables

列出所有表

sql
SELECT TABLE_SCHEMA, TABLE_NAME, TABLE_TYPE
FROM INFORMATION_SCHEMA.TABLES
ORDER BY TABLE_SCHEMA, TABLE_NAME;
sql
SELECT TABLE_SCHEMA, TABLE_NAME, TABLE_TYPE
FROM INFORMATION_SCHEMA.TABLES
ORDER BY TABLE_SCHEMA, TABLE_NAME;

Table Structure

表结构查询

sql
SELECT
  c.COLUMN_NAME,
  c.DATA_TYPE,
  c.CHARACTER_MAXIMUM_LENGTH,
  c.IS_NULLABLE,
  c.COLUMN_DEFAULT
FROM INFORMATION_SCHEMA.COLUMNS c
WHERE c.TABLE_SCHEMA = @schema AND c.TABLE_NAME = @table
ORDER BY c.ORDINAL_POSITION;
sql
SELECT
  c.COLUMN_NAME,
  c.DATA_TYPE,
  c.CHARACTER_MAXIMUM_LENGTH,
  c.IS_NULLABLE,
  c.COLUMN_DEFAULT
FROM INFORMATION_SCHEMA.COLUMNS c
WHERE c.TABLE_SCHEMA = @schema AND c.TABLE_NAME = @table
ORDER BY c.ORDINAL_POSITION;

Indexes

索引查询

sql
SELECT
  i.name AS IndexName,
  i.type_desc AS IndexType,
  i.is_unique,
  i.is_primary_key,
  STRING_AGG(c.name, ', ') AS Columns
FROM sys.indexes i
JOIN sys.index_columns ic ON i.object_id = ic.object_id AND i.index_id = ic.index_id
JOIN sys.columns c ON ic.object_id = c.object_id AND ic.column_id = c.column_id
WHERE i.object_id = OBJECT_ID(@tableName)
GROUP BY i.name, i.type_desc, i.is_unique, i.is_primary_key;
sql
SELECT
  i.name AS IndexName,
  i.type_desc AS IndexType,
  i.is_unique,
  i.is_primary_key,
  STRING_AGG(c.name, ', ') AS Columns
FROM sys.indexes i
JOIN sys.index_columns ic ON i.object_id = ic.object_id AND i.index_id = ic.index_id
JOIN sys.columns c ON ic.object_id = c.object_id AND ic.column_id = c.column_id
WHERE i.object_id = OBJECT_ID(@tableName)
GROUP BY i.name, i.type_desc, i.is_unique, i.is_primary_key;

Foreign Keys

外键查询

sql
SELECT
  fk.name AS FK_Name,
  tp.name AS ParentTable,
  cp.name AS ParentColumn,
  tr.name AS ReferencedTable,
  cr.name AS ReferencedColumn
FROM sys.foreign_keys fk
JOIN sys.foreign_key_columns fkc ON fk.object_id = fkc.constraint_object_id
JOIN sys.tables tp ON fkc.parent_object_id = tp.object_id
JOIN sys.columns cp ON fkc.parent_object_id = cp.object_id AND fkc.parent_column_id = cp.column_id
JOIN sys.tables tr ON fkc.referenced_object_id = tr.object_id
JOIN sys.columns cr ON fkc.referenced_object_id = cr.object_id AND fkc.referenced_column_id = cr.column_id
WHERE tp.name = @tableName;
sql
SELECT
  fk.name AS FK_Name,
  tp.name AS ParentTable,
  cp.name AS ParentColumn,
  tr.name AS ReferencedTable,
  cr.name AS ReferencedColumn
FROM sys.foreign_keys fk
JOIN sys.foreign_key_columns fkc ON fk.object_id = fkc.constraint_object_id
JOIN sys.tables tp ON fkc.parent_object_id = tp.object_id
JOIN sys.columns cp ON fkc.parent_object_id = cp.object_id AND fkc.parent_column_id = cp.column_id
JOIN sys.tables tr ON fkc.referenced_object_id = tr.object_id
JOIN sys.columns cr ON fkc.referenced_object_id = cr.object_id AND fkc.referenced_column_id = cr.column_id
WHERE tp.name = @tableName;

Best Practices

最佳实践

Security

安全规范

  1. Never concatenate strings in queries - use parameters
  2. Least privilege for application users
  3. Use schemas to organize and control access
  1. 切勿在查询中拼接字符串 - 请使用参数化查询
  2. 遵循最小权限原则为应用程序用户分配权限
  3. 使用schema来组织数据并控制访问权限

Performance

性能优化

  1. Avoid 
    SELECT *
    - list columns explicitly
  2. Use appropriate indexes for WHERE and JOIN
  3. Avoid functions on columns in WHERE (not sargable)
  4. Use 
    SET NOCOUNT ON
    in stored procedures
  5. Paginate with 
    OFFSET/FETCH
    or 
    ROW_NUMBER()
  1. 避免使用
    SELECT *
    - 请显式列出需要查询的列
  2. 为WHERE和JOIN条件使用合适的索引
  3. 避免在WHERE子句的列上使用函数（此类查询不具备sargable特性）
  4. 在存储过程中使用
    SET NOCOUNT ON
  5. 使用
    OFFSET/FETCH
    或
    ROW_NUMBER()
    实现分页查询