Introduction to C# Scripting for SQL Server DBAs

By:Jeffrey Yao || Related Tips:More > Database Administration

Problem

Since the Visual Studio 2015 Update 1 , Microsoft has introduced an interactive C# scripting technology inside the Visual Studio 2015 environment by a dedicated interactive window. In it we can write C# code and run the code on the fly with all C# language features and do something that otherwise would be very difficult to do in other languages. As a SQL Server DBA, is there anything I need to know about this new C# scripting technology?

Solution

C# scripting is an interesting technology that can take advantage of native advanced features of the C# language, such as LINQ, Parallel threads, Lambda expressions, etc. These features can make the life of a SQL Server DBA much easier by creating some innovative solutions to some tough tasks.

We will provide some introduction and examples on how to use C# interactively in Visual Studio 2015.

Environment Setup

First install Visual Studio 2015 Community (or above) version, note the Community version is freeC.

After installation, it is highly recommended to apply the latest Visual Studio 2015 Update 3 .

Using C# Interactively After starting VS 2015, go to menu [View] > [Other windows] > [C# Interactive], and we will see a new window opened at the bottom, as shown below.
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We can type #help to see the basic keyboard shortcuts and commands.

Two important commands are #r and #load, which will be demonstrated later.

#r is to load assembly files, such as DLL files #load is to load csx script files, which are text files with C# scripts. Example 1 - Some Basic DBA Work

In this example, we will explore some DBA tasks, such as finding the largest database in an instance, finding the SQL Server service account, doing a backup, etc.

In the code, we first load the SQL Server SMO DLL, using #r and then using a LINQ query to find the three largest databases on my local SQL Server instance.

#r "C:\Program Files\Microsoft SQL Server\110\SDK\Assemblies\Microsoft.SqlServer.Smo.dll"
using Microsoft.SqlServer.Management.Smo;
Server svr = new Server("localhost");
var dbs = (from d in svr.Databases.Cast<Database>()
where d.Status.ToString() == "Normal"
orderby d.Size descending
select d).Take(3);
foreach (var d in dbs) { Console.WriteLine($"{d.Name} = {d.Size}MB"); }

If you want to find the service account, just do this.

svr.ServiceAccount

Here is the snapshot running the script, which you can type in one line after another (just as I did).

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Now let's do a database full backup. In this example I am doing a backup of database [AdventureWorks2012] on my local default instance. // do a database backup
#r "C:\Program Files\Microsoft SQL Server\110\SDK\Assemblies\Microsoft.SqlServer.SmoExtended.dll"
using Microsoft.SqlServer.Management.Common;
BackupDeviceItem deviceitem = new BackupDeviceItem(@"c:\temp\advwks2012_bkup.bak", DeviceType.File);
Backup bkup = new Backup { Database = "AdventureWorks2012", Action = BackupActionType.Database, Incremental = false, Initialize = true, CompressionOption = BackupCompressionOptions.On };
bkup.Devices.Add(deviceitem);
bkup.SqlBackup(svr);

After this you will see a backup file is created as c:\temp\advwks2012_bkup.bak.

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Example 2 - Parallel Tasks

Many times we know we can do something in parallel, such as doing database backups, or running multiple scripts. In this example, there are 8 files (named f_n.sql, where n=1 to 8) in a specific folder c:\MyTest, each file has two lines of code like this.

insert into dbo.t (a) values (1); -- 1 for f_1.sql, 2 for f_2.sql and so on so forth until 8 for f_8.sql
waitfor delay '00:00:10'; I also create a table in my [mssqlTips] database as the following. use mssqltips
if object_id('dbo.t', 'U') is not null
drop table dbo.t;
go
create table dbo.t (a int, d datetime default getdate());
go When I run each file against this table, it will create a record with a unique value column [a] in this table. Now if I run the 8 files in sequence, it will take at least 80 seconds to finish because in each file, there is a WAITFOR 10 seconds statement.

But if I can execute the 8 files in parallel, assuming I can only start 7 threads at a time, meaning I can execute 7 files simultaneously, then it will take me around 20 seconds to finish because the first 7 simultaneous executions will take 10 seconds, and then the remaining one will take another 10 seconds.

In table dbo.t, I should see 7 rows with almost the same value for [d] column and a value about 10 seconds later for the other rows for the [d] column.

Let's see whether this works as expected. So here is the C# script.

using System.IO;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
string[] files = Directory.GetFiles(@"c:\Mytest\");
Parallel.ForEach(files, new ParallelOptions { MaxDegreeOfParallelism = 7 }, (cf) =>
{
string sql = System.IO.File.ReadAllText(cf);
using (SqlCommand cmd = new SqlCommand(sql))
{
using (SqlConnection conn = new SqlConnection("server=.;database=mssqltips;trusted_connection=true"))
{
conn.Open();
cmd.Connection = conn;
cmd.ExecuteNonQuery();
}
}
} ); After running the script, I go to SSMS and do a SELECT * FROM dbo.t , and I can see the following 7 rows with almost the same [d] value around 23:29: 28 , and one row with [d] value around 23:29: 38 , i.e. exactly 10 seconds later.

This means the parallel execution indeed works as expected.

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Example 3 - SQL Parser

Microsoft has a very powerful SQL parser function library provided via a DLL called Microsoft.SqlServer.TransactSql.ScriptDom.dll. The functions in this DLL are much easier to use with C# than PowerShell, because lots of functions use C# features such as delegates or interface like IList<T> etc.

In the first example, we will look at how to do a re-formatting for a SQL file, such as upper-casing all keywords and adding semi-columns after each statement, etc.

#r "C:\Program Files (x86)\Microsoft SQL Server\110\SDK\Assemblies\Microsoft.SqlServer.TransactSql.ScriptDom.dll"
using System.IO;
using Microsoft.SqlServer.TransactSql.ScriptDom;
var sqlparser = new TSql110Parser(false);
TSqlFragment frag;
IList<ParseError> ilError;
using (var sr = new StreamReader(@"c:\temp\test.sql"))
{ frag = sqlparser.Parse(sr, out ilError); }
if (ilError.Count > 0) { Console.WriteLine("Parse failed, cannot continue"); return; }
var gen = new Sql110ScriptGenerator();
using (var tw = new StreamWriter(@"c:\temp\test_fmt.sql"))