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Azure Synapse Dedicated SQL Pool统计指定表中各字段的空值、空字符串或零值比例

news 2025/7/4 12:13:58

-- 创建临时表存储结果
CREATE TABLE #Results (
    DatabaseName NVARCHAR(128),
    TableName NVARCHAR(128),
    ColumnName NVARCHAR(128),
    DataType NVARCHAR(128),
    NullOrEmptyCount INT,
    TotalRows INT,
    Percentage DECIMAL(10,2)
);

DECLARE @db_name SYSNAME = DB_NAME();  -- 获取当前数据库名
DECLARE @table_name SYSNAME;
DECLARE @column_name SYSNAME;
DECLARE @data_type SYSNAME;
DECLARE @sql NVARCHAR(MAX);

-- 定义表游标
DECLARE table_cursor CURSOR FOR
SELECT TABLE_NAME 
FROM INFORMATION_SCHEMA.TABLES 
WHERE TABLE_TYPE = 'BASE TABLE' 
  AND TABLE_CATALOG = @db_name;

OPEN table_cursor;

FETCH NEXT FROM table_cursor INTO @table_name;

WHILE @@FETCH_STATUS = 0
BEGIN
    -- 定义列游标
    DECLARE column_cursor CURSOR FOR
    SELECT COLUMN_NAME, DATA_TYPE 
    FROM INFORMATION_SCHEMA.COLUMNS 
    WHERE TABLE_NAME = @table_name 
      AND TABLE_CATALOG = @db_name;

    OPEN column_cursor;
    FETCH NEXT FROM column_cursor INTO @column_name, @data_type;

    WHILE @@FETCH_STATUS = 0
    BEGIN
        -- 构建动态SQL
        SET @sql = N'
        INSERT INTO #Results
        SELECT 
            ''' + @db_name + ''' AS DatabaseName,
            ''' + @table_name + ''' AS TableName,
            ''' + @column_name + ''' AS ColumnName,
            ''' + @data_type + ''' AS DataType,
            ';

        -- 根据数据类型处理逻辑
        IF @data_type IN ('varchar', 'nvarchar', 'char', 'nchar', 'text')
        BEGIN
            SET @sql += N'
            SUM(CASE WHEN ISNULL(TRIM([' + @column_name + ']), '''') = '''' THEN 1 ELSE 0 END),';
        END
        ELSE IF @data_type IN ('int', 'bigint', 'smallint', 'tinyint', 'decimal', 'numeric', 'float', 'real')
        BEGIN
            SET @sql += N'
            SUM(CASE WHEN ISNULL([' + @column_name + '], 0) = 0 THEN 1 ELSE 0 END),';
        END
        ELSE
        BEGIN
            SET @sql += N'
            SUM(CASE WHEN [' + @column_name + '] IS NULL THEN 1 ELSE 0 END),';
        END

        -- 添加行数和百分比计算
        SET @sql += N'
            COUNT(*) AS TotalRows,
            ROUND(
                (SUM(CASE WHEN ';
        
        IF @data_type IN ('varchar', 'nvarchar', 'char', 'nchar', 'text')
            SET @sql += N'ISNULL(TRIM([' + @column_name + ']), '''') = '''' '
        ELSE IF @data_type IN ('int', 'bigint', 'smallint', 'tinyint', 'decimal', 'numeric', 'float', 'real')
            SET @sql += N'ISNULL([' + @column_name + '], 0) = 0 '
        ELSE
            SET @sql += N'[' + @column_name + '] IS NULL ';

        SET @sql += N'THEN 1 ELSE 0 END) * 100.0) / 
                NULLIF(COUNT(*), 0), 
                2
            )
        FROM ' + QUOTENAME(@table_name) + ';';

        -- 执行动态SQL
        EXEC sp_executesql @sql;

        FETCH NEXT FROM column_cursor INTO @column_name, @data_type;
    END

    CLOSE column_cursor;
    DEALLOCATE column_cursor;

    FETCH NEXT FROM table_cursor INTO @table_name;
END

CLOSE table_cursor;
DEALLOCATE table_cursor;

-- 查询最终结果
SELECT 
    DatabaseName,
    TableName,
    ColumnName,
    DataType,
    NullOrEmptyCount,
    TotalRows,
    Percentage
FROM #Results
ORDER BY TableName, ColumnName;

-- 清理临时表
DROP TABLE #Results;

代码说明：

临时表创建：使用#Results临时表存储最终结果集
游标遍历：
- 外层游标遍历所有用户表
- 内层游标遍历每个表的所有列
动态SQL构建：
- 根据列数据类型生成不同的统计逻辑
- 字符串类型：使用TRIM()和空字符串判断
- 数值类型：使用0值判断
- 其他类型：直接判断NULL值
安全处理：
- 使用QUOTENAME()防止SQL注入
- 使用NULLIF()处理除零错误
结果输出：
- 包含数据库名、表名、列名、数据类型
- 统计空值/空字符串数量
- 显示总行数和百分比