For more information, take a look at the documentation Use a SELECT statement with a simple CASE...
Depending on the query plan for the UPDATE statement, the number of rows being modified, and the isolation level of the transaction, locks may be acquired at the page level or table level rather than the row level. To avoid these higher level locks, consider dividing update statements that ...
using (SqlConnection connection = new SqlConnection(connectionString)) { using (SqlCommand command = new SqlCommand(query, connection)) { connection.Open(); using (SqlDataReader reader = await command.ExecuteReaderAsync()) { if (await reader.ReadAsync()) { using (Stream stream = await reader....
For example, processing a query in parallel typically uses more resources than processing it serially, but completes the query faster. The SQL Server Query Optimizer will use a parallel execution plan to return results if the load on the server won't be adversely affected....
Conversion locks can be observed for a short period of time under different complex circumstances, sometimes while running concurrent processes. Serializable range scan, singleton fetch, delete, and insert Key-range locking ensures that the following operations are serializable: Range scan query Singleto...
To check current size and growth parameters fortempdb, use the following query: SQL SELECTnameASfile_name, type_descASfile_type,size*8.0/1024ASsize_mb, max_size *8.0/1024ASmax_size_mb,CAST(IIF(max_size =0,0,1)ASbit)ASis_autogrowth_enabled,CASEWHENgrowth =0THENgrowthWHENgrowth >0ANDis_...
For example, while a transaction date/time column could exist in the table, the day of the year (1 to 365) column is used as the partition key. In that case, using the query below to search over the date column may decrease performance,especially when the data size is vast and we do...
CREATE TABLE orders ( id INT AUTO_INCREMENT PRIMARY KEY, order_date DATE NOT NULL, ... ) PARTITION BY RANGE (YEAR(order_date)) ( PARTITION p0 VALUES LESS THAN (2010), PARTITION p1 VALUES LESS THAN (2011), ... ); 数据库设计优化 规范化(Normalization) 规范化是减少数据冗余和提高数据一...
Basically, I believe Chuck's query and my with a flip to >= should work if you're looking for each row. If the datediff(month, DeactiveDate, ReactiveDate) >=6 So, flip the >= in m...
query_1 UNION [DISTINCT | ALL] query_2 使用说明: 只使用union关键词和使用union disitnct的效果是相同的。由于去重工作是比较耗费内存的,因此使用union all操作查询速度会快些,耗费内存会少些。如果用户想对返回结果集进行order by和limit操作,需要将union操作放在子查询中,然后select from subquery,最后把subgqu...