Selecting default value SQL management studio - java

I have SQL Server and I am using SQL management studio. What I want is to select default value of column of multiple tables in database.
For example I have database DB. In DB I have 3 tables - tableA, tableB and tableC.
All of them have the same columns. What I want is to get default values of columns 'Customers' for tables A,B and C.
It must be something like this:
SELECT Column_Default
FROM Information_Schema.Columns
WHERE Table_Schema = DB AND
Table_Name like 'table%' and
Column_Name = 'Customers'
But there is error in Table_Schema = DB. I am not sure it should look like this as SQL syntax. It is working as MySQL but not here.


SELECT COLUMN_DEFAULT
FROM Information_Schema.Columns
WHERE Table_Schema = 'dbo'
AND TABLE_NAME IN ('A','B','C')
AND COLUMN_NAME = 'Customers'
You were close, you just needed single quotes around your table schema name, also using the IN operator to explicitly specify your table names instead of using your wildcard search can make the query more robust if if a new table of a similar name is created.

Related

H2 : Column not found when name has number in it

I have a column in my database table named '1GNics'. I can create the table in H2 using the following SQL
CREATE TABLE resource( ... 1GNics int DEFAULT NULL, ... );
This creates the table with the correct column name but if i try do a select it takes the select statement as follows and tries to select the top 1 from the table
SELECT 1 GNics from RESOURCE;
Even do the select statement reads
SELECT 1GNics from RESOURCE;
I am using hibernate to access the database so it is generating the select statements automatically. Is there a way of selecting this without changing the column name to 'oneGNics' ?

You can use HQL and use query as follows
session.createQuery("SELECT \"1GNics\" from RESOURCE");

Here is the query:
SELECT r.1GNics from RESOURCE AS r;
You can use alias of Table.

Run Oracle query from Java

I want to run the query: "DESCRIBE table_name;"
statement = this.connection.createStatement();
ResultSet rset = statement.executeQuery("DESCRIBE table_name");
and I got this error:
" java.sql.SQLSyntaxErrorException: ORA-00900: invalid SQL statement"
what is the problem?

DESC[RIBE] is a SQL*Plus command, not a SQL statement. The DESC command queries the Oracle data dictionary, something like:
select COLUMN_NAME, DATA_TYPE
from USER_TAB_COLUMNS
where TABLE_NAME = 'YOUR_TABLE'

DESC is a SQL*Plus command. SO, you cannot use it via JDBC/ODBC.
An alternative can be like this below.
select RPAD(COLUMN_NAME,30)||' '||DATA_TYPE||'('||DATA_LENGTH||')' as descr
FROM all_tab_cols
WHERE TABLE_NAME = UPPER('YOUR_TABLE') and owner=UPPER('SCHEMA_NAME');
all_tab_cols is a data dictionary table(view) which contains the table metadata
Oracle's Reference

describe user2.flights;
Here user2 is database name and flights is table name. Try this.
Or use next query
select *
from user_tab_columns
where table_name = 'MY_TABLE'
order by column_id;
Use this query.
column_id is the "order" of the column in the table.
You should ensure that 'MY_TABLE' is capitalised unless you've been adding tables with casing ( a bad idea ) in which case you need to use something like = "MyTable"

How to get Column names Column Data types Form Table using Eclipse Link/JPA

I am working on JPA. My requirement is get the Column Name and Data types from Table.
I have Query's to do that but those are Native Query's. If I used those Native Query's, Is It will support on any Data Base like Oracle, MySql,......
Now am Using MySql with JPA working fine.
Below Query for Getting Table Column Names
SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_SCHEMA = 'SchemaName'
AND TABLE_NAME = 'TableName';
I executed above Query using createNativeQuery() in JPA . Is it will support in all Data Bases. If not then how can I do this. Thank you very much.

In Oracle you can use ALL_TAB_COLUMNS table and in MS SQL server and MySQL you can use INFORMATION_SCHEMA.COLUMNS table to get information about tables and columns.
SELECT * FROM ALL_TAB_COLUMNS
WHERE OWNER = 'SchemaName' AND TABLE_NAME = 'TableName';

How select column names ,column data type, key column of a table in mysql

How select column names ,column data type, key column of a table in mysql by passing the table name.
I am using mysql 5.5

Pick the info you need from
SELECT *
FROM information_schema.columns
or
SELECT *
FROM information_schema.tables

Try this:
Get structure of table
DESCRIBE table;
SELECT * FROM information_schema.tables where table_name = 'table';
Get a list of the tables in your database.
SHOW TABLES;
Whole database structure
mysqldump database_name

Select database,
execute command using desc or SHOW FIELDS FROM.
Code:
`use testDB;`
``desc `testDB`.`images`;``
-- or
`SHOW FIELDS FROM images;`
See my previous answer How to show mysql table columns data type?, it solves your problem.
The results are shown in attached image file.

How can I detect a SQL table's existence in Java?

How can I detect if a certain table exists in a given SQL database in Java?

You can use DatabaseMetaData.getTables() to get information about existing tables.
This method works transparently and is independent of the database engine. I think it queries information schema tables behind the scenes.
Edit:
Here is an example that prints all existing table names.
DatabaseMetaData md = connection.getMetaData();
ResultSet rs = md.getTables(null, null, "%", null);
while (rs.next()) {
System.out.println(rs.getString(3));
}

Use java.sql.DatabaseMetaData.getTables(null, null, YOUR_TABLE, null). If the table exists, you will get a ResultSet with one record.
See DatabaseMetaData.getTables

For ALL ANSI-compliant databases:
(mySQL, SQL Server 2005/2008, Oracle, PostgreSQL, SQLLite, maybe others)
select 1 from information_schema.tables where table_name = #tableName

This is not a language-specific, but a database-specific problem. You'd query the metadata in the database for the existence of that particular object.
In SQL Server for instance:
SELECT * FROM sys.objects WHERE object_id = OBJECT_ID(N'[dbo].[table]')
AND type in (N'U')

Write a query that queries the table/view that will list the tables (this is different depending on DB vendor). Call that from Java.
Googling information_schema.tables will help a lot.

Depending on the DB, you can do (MySQL)
SHOW TABLES
or (Oracle)
SELECT * FROM user_objects WHERE object_type = 'TABLE'
or another thing for SQL Server. Cycle through the results for MySQL or further filter on the Oracle one.

Why not just see if it is in sysobjects (for SQL Server)?
SELECT [name] FROM [sysobjects] WHERE type = 'U' AND [name] = 'TableName'

There is a JDBC feature, database vendor independent - see [java.sql.DatabaseMetaData#getTables()][1]
You can get the DatabaseMetaData instance by calling java.sql.Connection#getMetaData()
[1]: http://java.sun.com/javase/6/docs/api/java/sql/DatabaseMetaData.html#getTables(java.lang.String, java.lang.String, java.lang.String, java.lang.String[])

This is what worked for me for jdbc:derby:
//Create Staff table if it does not exist yet
String tableName = "STAFF";
boolean exists = conn.getMetaData().getTables(null, null, tableName, null).next();
if(!exists){
s = conn.createStatement();
s.execute("create table staff(lastname varchar(30), firstname varchar(30), position varchar(20),salary double,age int)");
System.out.println("Created table " + tableName);
}
Note that tableName has to be all caps.

For MS Access:
Select Count(*) From MSysObjects
Where type=1 And name='your_table_name_here'

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