Requesting verification of this arguably complex SQL script - sql

Question

I'd appreciate it if some SQL experts can take a look at this script and verify if it will work or if it can be improved in anyway (performance, ease, etc.). So, considering the following:
Leads {
LeadId INT,
SourceId TINYINT,
PersonId INT,
PhoneId INT,
EmailId INT,
AddressId INT,
ImporterId SMALLINT,
ImportedDateTime DATETIME2(7)
}
Duplicates {
DuplicateId INT,
SourceId TINYINT,
LeadId INT,
ImporterId SMALLINT,
DuplicatedDateTime DATETIME2(7)
}
How will this script perform:
-- Outside variables provided as part of a stored procedure
DECLARE #SourceId TINYINT;
DECLARE #ImporterId SMALLINT;
PRINT 'Deleting the CSVTemp table if it exists';
IF ((SELECT CASE WHEN OBJECT_ID('CSVTemp') IS NOT NULL THEN 1 ELSE 0 END) = 1)
BEGIN
DROP TABLE [CSVTemp];
END
PRINT 'Creating the CSVTemp table';
CREATE TABLE [CSVTemp](
[FirstName] NVARCHAR(48),
[LastName] NVARCHAR(48),
[Phone] BIGINT,
[Email] VARCHAR(96),
[Street] VARCHAR(64),
[Zip] INT
);
PRINT 'Performing a BULK insert into CSVTemp';
BULK INSERT [CSVTemp] FROM '{File}.csv' WITH (FIELDTERMINATOR = ',', ROWTERMINATOR = '\n');
PRINT 'Adding IDENTITY column to CSVTemp';
ALTER TABLE [CSVTemp] ADD [Id] INT IDENTITY(1,1) NOT NULL;
PRINT 'Adding PK constraint to CSVTemp';
ALTER TABLE [CSVTemp] ADD CONSTRAINT [PK_CSVTemp] PRIMARY KEY CLUSTERED(
[Id] ASC
) WITH(
PAD_INDEX = OFF,
STATISTICS_NORECOMPUTE = OFF,
IGNORE_DUP_KEY = OFF,
ALLOW_ROW_LOCKS = ON,
ALLOW_PAGE_LOCKS = ON
) ON [PRIMARY];
PRINT 'Counting CSVTemp rows';
DECLARE #Count INT = (SELECT COUNT(1) FROM [CSVTemp]);
PRINT 'Declaring internal variables';
DECLARE #I INT = 0;
PRINT 'Looping through rows in CSVTemp';
WHILE (#I < (#Count + 1))
BEGIN
BEGIN TRANSACTION
DECLARE #FirstName NVARCHAR(48);
DECLARE #LastName NVARCHAR(48);
DECLARE #Phone BIGINT;
DECLARE #Email VARCHAR(96);
DECLARE #Street VARCHAR(64);
DECLARE #Zip INT;
SELECT #FirstName = [FirstName],
#LastName = [LastName],
#Phone = [Phone],
#Email = [Email],
#Street = [Street],
#Zip = [Zip] FROM [CSVTemp] WHERE ([Id] = #I);
DECLARE #LeadId INT = (
SELECT [Leads].[LeadId]
FROM [People].[Person]
JOIN [Management].[Leads] ON ([Leads].[PersonId] = [Person].[PersonId])
JOIN [Communication].[Phones] ON ([Leads].[PhoneId] = [Phones].[PhoneId])
WHERE (([Person].[FirstName] LIKE #FirstName) OR ([Person].[LastName] LIKE #LastName))
AND ([Phones].[PhoneId] = #Phone)
);
IF (#LeadId IS NOT NULL)
BEGIN
INSERT INTO [Management].[Duplicates]([SourceId], [LeadId], [ImporterId]) VALUES(#SourceId, #LeadId, #ImporterId);
END
ELSE
BEGIN
INSERT INTO [People].[Person]([FirstName], [LastName]) VALUES(#FirstName, #LastName);
DECLARE #PersonId INT = ##IDENTITY;
INSERT INTO [Communication].[Phones]([PhoneTypeId], [Number]) VALUES(6, #Phone);
DECLARE #PhoneId INT = ##IDENTITY;
INSERT INTO [Communication].[Emails]([Address]) VALUES(#Email);
DECLARE #EmailId INT = ##IDENTITY;
INSERT INTO [Location].[Addresses]([PostalCode], [Street]) VALUES(#Zip, #Street);
DECLARE #AddressId INT = ##IDENTITY;
INSERT INTO [Management].[Leads]([SourceId], [PersonId], [PhoneId], [EmailId], [AddressId], [ImporterId]) VALUES(#SourceId, #PersonId, #PhoneId, #EmailId, #AddressId, #ImporterId);
END
COMMIT
SET #I = (#I + 1);
END
PRINT 'Deleting CSVTemp table';
DROP TABLE [CSVTemp];
UPDATE
#Will/#Mitch, I don't know if you guys are still around, but I ended up finalizing the script by converting the WHILE loop to work with a CURSOR. I tested the script by looping through 10.5k rows and it took 3-5 seconds, which is fine with me. Sadly, I thought I fully understood what #Will was saying about the sets, but I couldn't come up with a way to improve it, so I'll leave it as is. If anyone is willing to give me an example script about what #Will was talking about, I would appreciate it, if not, then thank you #Will and #Mitch for the help so far.
Anyway, here's the updated WHILE loop that uses a CURSOR now.
DECLARE #Id INT = 0;
DECLARE C1 CURSOR READ_ONLY FOR (SELECT [Id] FROM [CSVTemp]);
OPEN C1;
FETCH NEXT FROM C1 INTO #Id;
WHILE (##FETCH_STATUS = 0)
BEGIN
BEGIN TRANSACTION
DECLARE #FirstName NVARCHAR(48);
DECLARE #LastName NVARCHAR(48);
DECLARE #Phone BIGINT;
DECLARE #Email VARCHAR(96);
DECLARE #Street VARCHAR(64);
DECLARE #Zip INT;
SELECT #FirstName = [FirstName],
#LastName = [LastName],
#Phone = [Phone],
#Email = [Email],
#Street = [Street],
#Zip = [Zip] FROM [CSVTemp] WHERE ([Id] = #Id);
DECLARE #LeadId INT = (
SELECT [Leads].[LeadId]
FROM [People].[Person]
JOIN [Management].[Leads] ON ([Leads].[PersonId] = [Person].[PersonId])
JOIN [Communication].[Phones] ON ([Leads].[PhoneId] = [Phones].[PhoneId])
WHERE (([Person].[FirstName] LIKE #FirstName) AND ([Person].[LastName] LIKE #LastName))
AND ([Phones].[Number] = #Phone)
);
IF (#LeadId IS NOT NULL)
BEGIN
INSERT INTO [Management].[Duplicates]([SourceId], [LeadId], [ImporterId]) VALUES (#SourceId, #LeadId, #ImporterId);
END
ELSE
BEGIN
INSERT INTO [People].[Person]([FirstName], [LastName]) VALUES(#FirstName, #LastName);
DECLARE #PersonId INT = SCOPE_IDENTITY();
INSERT INTO [Communication].[Phones]([PhoneTypeId], [Number]) VALUES(6, #Phone);
DECLARE #PhoneId INT = SCOPE_IDENTITY();
INSERT INTO [Communication].[Emails]([Address]) VALUES(#Email);
DECLARE #EmailId INT = SCOPE_IDENTITY();
INSERT INTO [Location].[Addresses]([PostalCode], [Street]) VALUES(#Zip, #Street);
DECLARE #AddressId INT = SCOPE_IDENTITY();
INSERT INTO [Management].[Leads]([SourceId], [PersonId], [PhoneId], [EmailId], [AddressId], [ImporterId]) VALUES(#SourceId, #PersonId, #PhoneId, #EmailId, #AddressId, #ImporterId);
END
COMMIT
FETCH NEXT FROM C1 INTO #Id;
END
CLOSE C1;
DEALLOCATE C1;

Answer 1

Don't use ##IDENTITY. Use SCOPE_IDENTITY():
SCOPE_IDENTITY and ##IDENTITY return
the last identity values that are
generated in any table in the current
session. However, SCOPE_IDENTITY
returns values inserted only within
the current scope; ##IDENTITY is not
limited to a specific scope.
For example, there are two tables, T1 and
T2, and an INSERT trigger is defined
on T1. When a row is inserted to T1,
the trigger fires and inserts a row in
T2. This scenario illustrates two
scopes: the insert on T1, and the
insert on T2 by the trigger.
Assuming that both T1 and T2 have
identity columns, ##IDENTITY and
SCOPE_IDENTITY will return different
values at the end of an INSERT
statement on T1. ##IDENTITY will
return the last identity column value
inserted across any scope in the
current session. This is the value
inserted in T2. SCOPE_IDENTITY() will
return the IDENTITY value inserted in
T1. This was the last insert that
occurred in the same scope. The
SCOPE_IDENTITY() function will return
the null value if the function is
invoked before any INSERT statements
into an identity column occur in the
scope.