I named my tables as Employee and Department whereas in MSSMS it is displayed as dbo.Employee and dbo.Department respectively and the query works if I use either of them, Why is it so?
dbo schema is the default schema when you create tables, views and etc in SQL Server.
When you create a table it will be placed in default schema and you can call it like dbo.tableName or just tableName.
Schemas
SQL Server ships with ten pre-defined schemas that have the same names as the built-in database users and roles. These exist mainly for backward compatibility. You can drop the schemas that have the same names as the fixed database roles if you do not need them.
You cannot drop the following schemas:
Default schemas :
dbo
guest
sys
INFORMATION_SCHEMA
For more info see : Microsoft SQL Server schemas
You can create your schemas to allow you to better manage your objects too.
dbo is a so-called schema. This is similar to a folder.
Every table, view, procedure, etc. is always put into a schema.
But if you don't specify the schema, then dbo is used.
Related
I am new to SQL Server. I connected to SQL server via SQuirrel Client.
Connection URL:
jdbc:sqlserver://192.xx.xx.xx:1433;databaseName=ep
with username & password.
Then I tried a query on table1 in schema1 -
SELECT * from table1
It returned records. I did not mention schema name in query.
There may be possibility of having tables in different sachems (same database) with same name.
Am I right? If yes, then how will it resolve schema name?
Schema work like a namespace in SQL SERVER, you can create tables, views, sps under a schema and set GRANT, DENY, or REVOKE permissions on those objects. From Implementation of Database Object Schemas
SQL Server 2005 implemented the concept of a database object schema. A schema is a distinct namespace to facilitate the separation, management, and ownership of database objects. It removed the tight coupling of database objects and owners to improve the security administration of database objects. Database object schemas offer functionality to control and help secure application objects within a database environment not available in previous versions of SQL Server.
Just wanted to add here, if you have not specified any schema than, it select dbo as schema.
It is distinguished by its owner. Every object (table ,view ,proc) has an owner which must be a user in the database. For example you may have user1.table1 and user2.table2 in the same database.
So you may type
select * from user1.table1
and
select * from user2.table1
You may see names like dbo.table_name, this means that the owner is the dbo, the database owner. If you do not specify an owner then the system checks dbo and your user (the user that run the command)
My database has been created with table names looking like this for the user information:
DROP TABLE [dbo].[webpages_Membership];
DROP TABLE [dbo].[webpages_OAuthMembership];
DROP TABLE [dbo].[webpages_Roles];
DROP TABLE [dbo].[webpages_UsersInRoles];
Is this somewhat of a standard when it comes to table naming conventions? If I now want
to make some new tables would it be reasonable to also name them things like
admin_application
admin_account
or do DBAs normally assign tables used to hold different things to different users when they want to group table types?
I would just like to find out how people normally group tables in an application. Am I
right to assume they are all under one owner in this case dbo or do people leave the
table names alone and have them stored in different owner accounts?
Yes, the best way is to use schemas to divide logically grouped tables. Good example of this is Adventure works database you can download from CodePlex. They have several schemas for different parts of the company such as Person, Production, Purcahsing, Sales and other. See more details on how MS designed this DB.
Have a look at schemas:
create schema webpages authorization dbo;
GO
create table webpages.Membership (...
create table webpages.OAuthMembership (...
create schema admin authorization dbo;
GO
create table admin.application (...
It used to be that before SQL Server 2005, you needed to create a database user in order to create a schema. However, since then, you can create schemas for organizational purposes. Schemas cannot contain schemas, so it's a single level. Schemas can contain any database object, i.e. tables, stored procedures, etc..
Schemas need to have an owner, hence the authorization bit above. Specifying dbo here will make it the same as if you had created it in the dbo schema.
is there a way to group tables into Postgres's schema like structure? We have a Postgresql server we want to move to Oracle DB. We use a lot of schemas to categorize tables. Anything Similar in oracle? Oracle has Schemas but there is a one to one relation between schema and a user. Schema == User.
Is there another stack-exchange that might be more appropriate for this question?
You will need to create the same amount of schemas in Oracle as you did in PostgreSQL. The fact that each schema is also associated with a user should not bother you.
You don't have to log-in with all those users if that's what you are wondering.
Just create one "application" user, and grant the necessary privileges on the tables you create in the various schemas to that application user.
If you used PostgreSQL's search path feature to avoid fully qualified table names, then you'll need to create synonyms (owned by the "applicatoin" user) that point to the tables in the various schemas.
I'm converting database from Teradata to SqlServer. I've noticed all tables and procedures are named by the prefix "dbo." (e.g. "dbo.Table1").
I would like to know if and how I can get rid of "dbo" because it would make the conversion task a lot more easier.
dbo is not part of the table name. It is the name of the schema that the tables and stored procedures are attached to. dbo is the default schema in SQL server, though you can add others if needed.
See this MSDN article about them.
dbo is the schema, you can specify a new schema if you like. dbo is default is sql server.
All tables have to go into a schema. As durilai says, dbo is the "default" schema for SQL Server (it always exists). However, note that different users can have different default schemas (if more than one exists).
If you make reference to a table without specifying the schema, then SQL Server will search in your default schema for it (and the same goes for any other objects).
So, if your default schema is dbo, the following two statements are equivalent:
select * from Table1
select * from dbo.Table1
dbo is the default schema in SQL Server if no schema was set by user,
if you want you can create new schema and create tables to it.
Schemas are useful. For example, I used to grant an app login execute permission to every stored procedure separately. Now I grant the app login execute permission to the schema that contains all the stored procedures. This is much easier.
At least on my local instance, when I create tables, they are all prefixed with "dbo.". Why is that?
dbo is the default schema in SQL Server. You can create your own schemas to allow you to better manage your object namespace.
If you are using Sql Server Management Studio, you can create your own schema by browsing to Databases - Your Database - Security - Schemas.
To create one using a script is as easy as (for example):
CREATE SCHEMA [EnterSchemaNameHere] AUTHORIZATION [dbo]
You can use them to logically group your tables, for example by creating a schema for "Financial" information and another for "Personal" data. Your tables would then display as:
Financial.BankAccounts
Financial.Transactions
Personal.Address
Rather than using the default schema of dbo.
It's new to SQL 2005 and offers a simplified way to group objects, especially for the purpose of securing the objects in that "group".
The following link offers a more in depth explanation as to what it is, why we would use it:
Understanding the Difference between Owners and Schemas in SQL Server
Microsoft introduced schema in version 2005. For those who didn’t know about schema, and those who didn’t care, objects were put into a default schema dbo.
dbo stands for DataBase Owner, but that’s not really important.
Think of a schema as you would a folder for files:
You don’t need to refer to the schema if the object is in the same or default schema
You can reference an object in a different schema by using the schema as a prefix, the way you can reference a file in a different folder.
You can’t have two objects with the same name in a single schema, but you can in different schema
Using schema can help you to organise a larger number of objects
Schema can also be assigned to particular users and roles, so you can control access to who can do what.
You can generally access any object from any schema. However, it is possible to control which users have which access to particular schema, so you can use schema in your security model.
Because dbo is the default, you normally don’t need to specify it within a single database:
SELECT * FROM customers;
SELECT * FROM dbo.customers;
mean the same thing.
I am inclined to disagree with the notion of always using the dbo. prefix, since the more you clutter your code with unnecessary detail, the harder it is to read and manage.
For the most part, you can ignore the schema. However, the schema will make itself apparent in the following situations:
If you view the tables in either the object navigator or in an external application, such as Microsoft Excel or Access, you will see the dbo. prefix. You can still ignore it.
If you reference a table in another database, you will need its full name in the form database.schema.table:
SELECT * FROM bookshop.dbo.customers;
For historical reasons, if you write a user defined scalar function, you will need to call it with the schema prefix:
CREATE FUNCTION tax(#amount DECIMAL(6,2) RETURNS DECIMAL(6,2) AS
BEGIN
RETURN #amount * 0.1;
END;
GO
SELECT total, dbo.tax(total) FROM pricelist;
This does not apply to other objects, such as table functions, procedures and views.
You can use schema to overcome naming conflicts. For example, if every user has a personal schema, they can create additional objects without having to fight with other users over the name.
Something from Microsoft (Documentation)
The dbo user is a special user principal in each database. All SQL Server administrators, members of the sysadmin fixed server role, sa login, and owners of the database, enter databases as the dbo user. The dbo user has all permissions in the database and cannot be limited or dropped. dbo stands for database owner, but the dbouser account is not the same as the db_owner fixed database role, and the db_owner fixed database role is not the same as the user account that is recorded as the owner of the database.
The dbo user owns the dbo schema. The dbo schema is the default schema for all users, unless some other schema is specified. The dbo schema cannot be dropped.
The dbo user owns the dbo schema. The dbo schema is the default schema for all users, unless some other schema is specified. The dbo schema cannot be dropped.
DBO is the default schema in SQL Server. You can create your own schemas to allow you to better manage your object namespace. As a best practice, I always add the "DBO." prefix even though it is not necessary. Most of the time in SQL it's good to be explicit.