選擇不同表中的記錄數

Question

我想在一個存儲過程中獲得此查詢的結果。與此查詢我想在table1返回的行數table4

select count(*) from table1 
select count(*) from table2 
select count(*) from table3 
select count(*) from table4 

我想有這樣的結果在一個臨時表，並選擇臨時表中的所有列。

Answer 1

這裏有一個不是很優雅的解決方案：

SELECT 'table1' as table_name, COUNT(*) as record_count from table1 
UNION ALL 
SELECT 'table2' as table_name, COUNT(*) as record_count from table2 
UNION ALL 
SELECT 'table3' as table_name, COUNT(*) as record_count from table3 
UNION ALL 
SELECT 'table4' as table_name, COUNT(*) as record_count from table4 

Answer 2

myCommand.CommandType = CommandType.StoredProcedure; 
    myCommand.Connection = myConnection; 
    myCommand.CommandText = "MyProc"; 

    try 
    { 
     myConnection.Open(); 

     myReader = myCommand.ExecuteReader();  
     while (myReader.Read()) 
     { 
       //Write logic to process data for the first result. 
     } 

     myReader.NextResult(); 
     while (myReader.Read()) 
     { 
       //Write logic to process data for the second result. 
     } 
    } 
    catch(Exception ex) 
    { 
     // catch exceptions 
    } 
    finally 
    { 
     myConnection.Close(); 
    } 

Answer 3

假設SQL Server中，我發現dm_db_partition_stats是一種可靠的方式來獲得行數迅速：

SELECT [TableName] = '[' + s.name +'].[' + t.name + ']' 
, [RowCount] = SUM(p.row_count)OVER(PARTITION BY t.object_id) 
FROM sys.tables t 
JOIN sys.schemas s ON s.schema_id = t.schema_id 
JOIN sys.dm_db_partition_stats p ON p.object_id = t.object_id 
WHERE t.[type] = 'U' 
AND p.index_id IN (0,1) 
AND t.name IN ('table1','table2','table3','table4') --Just table names here, but it's best practice to also include schemas 
ORDER BY s.name, t.name 

Answer 4

INSERT INTO #temp 
SELECT * FROM 
(

    select Cnt = count(*) from table1 Union All 
    select count(*) from table2 Union All 
    select count(*) from table3 Union All 
    select count(*) from table4 
)X 

DROP TABLE #temp 

Answer 5

要做到這一點在一條記錄中，你可以這樣做：

SELECT (SELECT COUNT(*) from table1) table1_rec_count, 
     (SELECT COUNT(*) from table2) table2_rec_count, 
     (SELECT COUNT(*) from table3) table3_rec_count, 
     (SELECT COUNT(*) from table4) table4_rec_count 

再次，這不是一個優雅的解決方案。