Microsoft SQL Server/Table manipulation

Introduction

The DDL and DML respect the SQL-86 norm. However, in addition to the requests SELECT, UPDATE, INSERT we find MERGE since the 2008 version.

Create a table

In SSMS, a right click on the folder "Tables" of a database allows to add one.

A right click on a particular table lets choose between:

1. Modify the table structure (add a column, modify a type).
2. Select its 1,000 first records (TOP), or the 1,000 last (ORDER BY id DESC).
3. Edit its 200 first.

Otherwise in SQL one must enter:

CREATE TABLE [dbo].[table1] (
	[Nom] [varchar](250) NULL,
	[Prénom] [varchar](250) NULL,
	[identifiant] [int] IDENTITY(1,1) NOT NULL)

Filling the first columns:

INSERT INTO table1 VALUES ('Doe', 'Jane', 1), ('Doe', 'John', 2)

To aim some other columns, the fields must be precised. For example, by filling the first name, the last name will be null:

INSERT INTO table1 (First_name, id) VALUES ('Jane', 3)

From another table:

INSERT INTO table1 (First_name, id)
SELECT First_name, ID FROM table2

Update:

UPDATE table1
SET First_name = 'Janet'
WHERE ID = 3

UPDATE table1
SET First_name = t2.First_name, Last_name = t2.Last_name
FROM table1 t1
INNER JOIN table2 t2 on t1.ID = t2.ID_t1

Create an index

The software PK abbreviation means "primary key".

To create a foreign key, drop down the table, in the menu Keys, right click, new foreign key..., the list of all the table foreign keys appears in a small window (named by default "FK_..." for "foreign key").

In General, Tables and columns specification, click on "..." to select the table and its field to link.

Add a unique id

Normally each table should own at least one unique id (primary key). However, it's impossible to modify an existing column to attribute the property AUTOINCREMENT needed to such a key.

So to add one:

ALTER TABLE table1 ADD id int NOT NULL IDENTITY (1,1) PRIMARY KEY

Copy a table

The selection below clones a table with the same fields sizes:

SELECT * INTO table2 FROM table1

Knowing that the table spt_values from the system database master contains a sequential field number, it becomes possible to generate tables with this counter:

SELECT DISTINCT number 
FROM master.dbo.spt_values
WHERE number BETWEEN 2 AND 10

Where:

SELECT DISTINCT 'Line ' + convert(varchar, number, 112) as N into #BlankTable
FROM master.dbo.spt_values
WHERE number BETWEEN 2 AND 10

SELECT * from #BlankTable

N
Line 10
Line 2
Line 3
Line 4
Line 5
Line 6
Line 7
Line 8
Line 9

Import a table

From an array (Excel or Calc) converted for example in CSV encoded in PC DOS, to import it as a new table :

CREATE TABLE Array_to_Table (
  [Champ1] [varchar](500) NULL,
  [Champ2] [varchar](500) NULL,
  [Champ3] [varchar](500) NULL
)
GO
BULK INSERT Array_to_Table
FROM 'C:\Users\superadmin\Desktop\Array1.csv'
WITH (
  FIELDTERMINATOR = ';',
  ROWTERMINATOR = '\n'
)
GO
-- Displays the result
SELECT * from Array_to_Table
GO

Delete a table

To delete a whole table (data and structure):

DROP TABLE table1

To truncate a table, that is to say to conserve only the headers and columns types, by removing all records:

TRUNCATE TABLE table1
--or
DELETE table1

To delete certain lines from a table:

DELETE table1 WHERE Condition

NB: by adding OUTPUT deleted.* before the WHERE, we get the deleted content instead of the deleted lines number.}}

Research a table

To research a table which we know the exact name, on all the server databases:

sp_MSforeachdb 'USE ?
IF EXISTS (SELECT * FROM dbo.sysobjects WHERE id = OBJECT_ID(N''[MyTable]'') AND OBJECTPROPERTY(id, N''IsUserTable'') = 1)
BEGIN
  PRINT ''Table found in the database: ?''
END'

Research in all the tables

SSMS 10 doesn't propose any research function, like one could find it in phpMyAdmin for MySQL for example.

Table research

This script passes through each database to return the tables which names contain the specified string of characters (at the end):

ALTER Proc FindTable
@TableName nVarchar(50)
As
/*
Purpose : Search for a Table in all databases
Author : Sandesh Segu
Date : 17th July 2009
Version : 1.0
More Scripts  : http://sanssql.blogspot.com
*/
ALTER Table #temp (DatabaseName varchar(50),SchemaName varchar(50),TableName varchar(50))

Declare @SQL Varchar(500)
Set @SQL='Use [?] ;
if exists(Select name from sys.tables where name like '''+@TableName+''') 
insert into #temp 
Select ''?'' AS DatabaseName ,SS.Name AS SchemaName ,ST.Name AS TableName from sys.tables as ST , sys.schemas SS 
where ST.Schema_ID=SS.Schema_ID and ST.name like '''+@TableName+''''

EXEC sp_msforeachdb @SQL

Select * from #temp

Drop table #temp
GO

/* 
Usage: If the exact table name is known then specify the table name else include the wild cards
EXEC FindTable 'Employee'*/
EXEC FindTable '%String of characters to research%'

Research a value

A field value research in all the tables take a few time:

CREATE TABLE #result(
  id      INT IDENTITY,
  tblName VARCHAR(255),
  colName VARCHAR(255),
  qtRows  INT
)
go

DECLARE @toLookFor VARCHAR(255)
SET @toLookFor = '%String of characters%'

DECLARE cCursor CURSOR LOCAL FAST_FORWARD FOR
SELECT
  '[' + usr.name + '].[' + tbl.name + ']' AS tblName,
  '[' + col.name + ']' AS colName,
  LOWER(typ.name) AS typName
FROM
  sysobjects tbl
    INNER JOIN(
      syscolumns col
        INNER JOIN systypes typ
        ON typ.xtype = col.xtype
    )
    ON col.id = tbl.id
    --
    LEFT OUTER JOIN sysusers usr
    ON usr.uid = tbl.uid

WHERE tbl.xtype = 'U'
  AND LOWER(typ.name) IN(
        'char', 'nchar',
        'varchar', 'nvarchar',
        'text', 'ntext'
      )
ORDER BY tbl.name, col.colorder
--
DECLARE @tblName VARCHAR(255)
DECLARE @colName VARCHAR(255)
DECLARE @typName VARCHAR(255)

DECLARE @sql  NVARCHAR(4000)
DECLARE @crlf CHAR(2)

SET @crlf = CHAR(13) + CHAR(10)

OPEN cCursor
FETCH cCursor
INTO @tblName, @colName, @typName

WHILE @@fetch_status = 0
BEGIN
  IF @typName IN('text', 'ntext')
  BEGIN
    SET @sql = ''
    SET @sql = @sql + 'INSERT INTO #result(tblName, colName, qtRows)' + @crlf
    SET @sql = @sql + 'SELECT @tblName, @colName, COUNT(*)' + @crlf
    SET @sql = @sql + 'FROM ' + @tblName + @crlf
    SET @sql = @sql + 'WHERE PATINDEX(''%'' + @toLookFor + ''%'', ' + @colName + ') > 0' + @crlf
  END
  ELSE
  BEGIN
    SET @sql = ''
    SET @sql = @sql + 'INSERT INTO #result(tblName, colName, qtRows)' + @crlf
    SET @sql = @sql + 'SELECT @tblName, @colName, COUNT(*)' + @crlf
    SET @sql = @sql + 'FROM ' + @tblName + @crlf
    SET @sql = @sql + 'WHERE ' + @colName + ' LIKE ''%'' + @toLookFor + ''%''' + @crlf
  END

  EXECUTE sp_executesql
            @sql,
            N'@tblName varchar(255), @colName varchar(255), @toLookFor varchar(255)',
            @tblName, @colName, @toLookFor

  FETCH cCursor
  INTO @tblName, @colName, @typName
END

SELECT *
FROM #result
WHERE qtRows > 0
ORDER BY id
GO

DROP TABLE #result
go