PL/SQL isone of the most widely used programming languages when it comes to database programming. However, some essential concepts of PL/SQL need to learn and understand clearly by a PL/SQL programmer to use them properly. The cursor is one of them. In the PL/SQL program, SQL statements...
We can say that a Subquery or Inner Query is a SQL query that can be used as a condition for the main SQL query outside that helps to restrict the data rows to be fetched from the tables embedded within the WHERE clause. This query could not be bounded in a set function. For exampl...
然而,只有Index record lock 是需要的 用于语句 锁定记录使用一个unique index 来搜索唯一行 2.SELECT ... FROM ... LOCK IN SHARE MODE 设置共享next-key locks 在所有的搜索遇到的index 记录。 然而, 只有一个index record lock 是需要的用于语句 锁定记录使用一个unique index 来搜索唯一的记录 3.SELECT ....
Different versions of SQL Server will continue producing a separate set of elements in Showplan XML. However, the Unified Showplan Schema is backward-compatible. More information This update is included in the following service packs for SQL Server: Service Pack 2 for SQL Server 2016 Service Pack ...
If you upgraded from SQL Server Express, you must perform extra steps before you can use your upgraded instance of SQL Server: Enable the SQL Server Agent service in Windows SCM. Configure the SQL Server Agent service account by using SQL Server Configuration Manager. ...
In this scenario, when you use the ASCII function to convert the column in the Publisher and Subscriber database tables, different results are returned. You can refer to the following sample:Convert the column (col1) in the Publisher database table: SQL Kopiraj ...
Unit testingis a type of software testing which is done on an individual unit or component to test its corrections. Typically, Unit testing is done by the developer at the application development phase. Each unit in unit testing can be viewed as a method, function, procedure, or object. Dev...
Check if the query uses UDFs that do string manipulations or do extensive processing on data columns in the SELECT list. Check if the query contains loops, function recursions, or nestings.Diagnose environment differencesCheck the following questions and determine whether the comparison between the tw...
This article describes the possible rounding differences that can appear in DAX. They are related to the data types and the operation being performed: knowi
Alocking read, anUPDATE, or aDELETEgenerally set record locks on every index record that is scanned in the processing of an SQL statement. It does not matter whether there areWHEREconditions in the statement that would exclude the row.InnoDBdoes not remember the exactWHEREcondition, but only ...