How To Find The BigQuery Table Required Columns - google-bigquery

I have a table in the BigQuery that I would like to know what fields are required. How do I do that? Thanks in advance!
I tried the following queries, but none of them tell me the required field information.
SELECT * FROM mydataset.INFORMATION_SCHEMA.TABLES;
SELECT column_name, data_type
FROM `myprojectid`.mydataset.INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'mytablename'

Add is_nullable column:
SELECT column_name, data_type, is_nullable
FROM `myprojectid`.mydataset.INFORMATION_SCHEMA.COLUMNS
WHERE table_name = 'mytablename'

Related

Data type sql database

I have a sql database and are trying to get the datatype of a column
Database: "dbo.Parts"
Table: "miniParts"
I tried the following using Microsoft SSMS
SELECT DATA_TYPE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE
TABLE_NAME = "miniPARTS" AND COLUMN_NAME = "Date"
I get the following errors:
Invalid column name "dbo.PARTS"
Invalid column name "Date"
any ideas??
Try this :
SELECT COLUMN_NAME,
DATA_TYPE,
IS_NULLABLE,
CHARACTER_MAXIMUM_LENGTH,
NUMERIC_PRECISION,
NUMERIC_SCALE
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME='your_table_name';

How to fetch Column Names from Table?

I am trying to fetch column names form Table in Oracle. But I am not getting Column Names.
I used Many query's, And Find may query's in Stack overflow But I didn't get answer.
I used below query's:
1. SELECT COLUMN_NAME FROM USER_TAB_COLUMNS WHERE TABLE_NAME='TABLE_NAME';
2. SELECT COLUMN_NAME from ALL_TAB_COLUMNS where TABLE_NAME='TABLE_NAME';
But Out Put is
no row selected
What is the problem here. Thank you very much
both of the queries are correct, just the thing which can cause this problem is that ,maybe you did n't write your table name with capital letters you must do something like this:
SELECT COLUMN_NAME FROM ALL_TAB_COLUMNS
where TABLE_NAME = UPPER('TABLE_NAME');
OR
SELECT COLUMN_NAME FROM USER_TAB_COLUMNS
where TABLE_NAME = UPPER('TABLE_NAME');
Try this:
SELECT column_name
FROM all_tab_cols
WHERE upper(table_name) = 'TABLE_NAME'
AND owner = ' || +_db+ || '
AND column_name NOT IN ( 'password', 'version', 'id' )
or
SELECT COLUMN_NAME FROM ALL_TAB_COLUMNS where TABLE_NAME = UPPER('TABLE_NAME');
I hope This query would help yu out
SELECT SCHEMA_NAME (schema_id) + '.' + t.name AS 'Table Name'
FROM sys.tables t
INNER JOIN sys.columns c
ON c.object_id = t.object_id
WHERE c.name like '%hmy%
ORDER BY 'Table Name'

Position of a column in a table

How to know the Column position in a table in MS-SQL.
Eg: if a table consists of 3 columns namely column1, column2 and column3.
I should write a query so that i can get the position of column3 as 3
You will get all these from information_schema.
select ordinal_position from information_schema.columns
where schema_name = 'databasename'
and table_name = 'tablename'
and column_name = 'column name'
There're two ways to do this:
select colid
from sys.syscolumns
where id = object_id('schemaname.tablename') and name = 'column3'
and
select ordinal_position
from information_schema.columns
where
schema_name = 'schemaname' and
table_name = 'tablename' and
column_name = 'column3'
Here's an article about why you have to avoid information_schema views - The case against INFORMATION_SCHEMA views, I don't have to write this types of query often, so I don't really care about it, but sys.syscolumns tends to be a bit faster because it doesn't have many redundant joins which you may not need.
OTOH, information_schema views are ISO standard - here's dicussion about this - SQL Server: should I use information_schema tables over sys tables?
try :
SELECT ORDINAL_POSITION
FROM information_schema.columns
WHERE table_name = 'YourTableName' AND COLUMN_NAME = 'YourColumnName'
Try the query and check for the result.
select column_name,ordinal_position
from information_schema.columns
where table_catalog = 'yourdatabasename'
and table_schema = 'yourschemaname'
and table_name = 'yourtablename'

Finding the specific column (field) name from multiple tables in a database

I have large numbers of tables in my database. I am searching for a column named Country, but don't know which table contains that column. Is there a specific query that will help me to find the name of the table containing this column?
Yes, you can use INFORMATION_SCHEMA.COLUMNS
SELECT DISTINCT
TABLE_NAME
FROM
INFORMATION_SCHEMA.COLUMNS WHERE COLUMN_NAME = 'Country'
SELECT t.name AS table_name,
SCHEMA_NAME(schema_id) AS schema_name,
c.name AS column_name
FROM sys.tables AS t
INNER JOIN sys.columns c ON t.OBJECT_ID = c.OBJECT_ID
WHERE c.name LIKE '%ColumnName%'
ORDER BY schema_name, table_name;
Replace ColumnName to your actual column name
select distinct table_schema, table_name from information_schema.columns where table_name = 'Country';
You can find such of information in the INFORMATION_SCHEMA.COLUMNS
USE YourDBName;
SELECT DISTINCT Table_Name
FROM INFORMATION_SCHEMA.COLUMNS
WHERE Column_Name = 'Country';
If we want to find a column name with like operator in more than one tables (ex: 3 tables) then go for below query:
select COLUMN_NAME, TABLE_NAME
from ALL_TAB_COLUMNS
where TABLE_NAME in ('SIL_RLS_UPLOAD_TMP','SIL_CUSTOMER_MST','SIL_PERSONAL_CUSTOMER_MST')
and upper(column_name) like upper('%loan%');
If we want to find a column name with like operator in all tables then go for below query:
select *
from all_tab_columns
where upper(column_name) like upper('%card%');

How can I get column names from a table in Oracle?

I need to query the database to get the column names, not to be confused with data in the table. For example, if I have a table named EVENT_LOG that contains eventID, eventType, eventDesc, and eventTime, then I would want to retrieve those field names from the query and nothing else.
I found how to do this in:
Microsoft SQL Server
MySQL
PostgreSQL
But I need to know: how can this be done in Oracle?
You can query the USER_TAB_COLUMNS table for table column metadata.
SELECT table_name, column_name, data_type, data_length
FROM USER_TAB_COLUMNS
WHERE table_name = 'MYTABLE'
In SQL Server...
SELECT [name] AS [Column Name]
FROM syscolumns
WHERE id = (SELECT id FROM sysobjects WHERE type = 'V' AND [Name] = 'Your table name')
Type = 'V' for views
Type = 'U' for tables
You can do this:
describe EVENT_LOG
or
desc EVENT_LOG
Note: only applicable if you know the table name and specifically for Oracle.
For SQL Server 2008, we can use information_schema.columns for getting column information
SELECT *
FROM information_schema.columns
WHERE table_name = 'Table_Name'
ORDER BY ordinal_position
For SQLite I believe you can use something like the following:
PRAGMA table_info(table-name);
Explanation from sqlite.org:
This pragma returns one row for each column in the named table. Columns in the result set include the column name, data type, whether or not the column can be NULL, and the default value for the column. The "pk" column in the result set is zero for columns that are not part of the primary key, and is the index of the column in the primary key for columns that are part of the primary key.
See also: Sqlite.org Pragma Table Info
That information is stored in the ALL_TAB_COLUMNS system table:
SQL> select column_name from all_tab_columns where table_name = 'DUAL';
DUMMY
Or you could DESCRIBE the table if you are using SQL*PLUS:
SQL> desc dual
Name Null? Type
----------------------------------------------------- -------- ---------------------- -------------
DUMMY VARCHAR2(1)
The other answers sufficiently answer the question, but I thought I would share some additional information. Others describe the "DESCRIBE table" syntax in order to get the table information. If you want to get the information in the same format, but without using DESCRIBE, you could do:
SELECT column_name as COLUMN_NAME, nullable || ' ' as BE_NULL,
SUBSTR(data_type || '(' || data_length || ')', 0, 10) as TYPE
FROM all_tab_columns WHERE table_name = 'TABLENAME';
Probably doesn't matter much, but I wrote it up earlier and it seems to fit.
For Oracle
SELECT column_name FROM user_tab_cols WHERE table_name=UPPER('tableName');
describe YOUR_TABLE;
In your case :
describe EVENT_LOG;
Even this is also one of the way we can use it
select * from product where 1 != 1
select column_name,* from information_schema.columns
where table_name = 'YourTableName'
order by ordinal_position
For MySQL, use
SELECT column_name
FROM information_schema.columns
WHERE
table_schema = 'Schema' AND table_name = 'Table_Name'
For SQL Server:
SELECT [name] AS [Column Name]
FROM syscolumns
WHERE id = object_id('TABLE_NAME')
SELECT COLUMN_NAME 'all_columns'
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME='user';
You could also try this, but it might be more information than you need:
sp_columns TABLE_NAME
SELECT A.COLUMN_NAME, A.* FROM all_tab_columns a
WHERE table_name = 'Your Table Name'
AND A.COLUMN_NAME = 'COLUMN NAME' AND a.owner = 'Schema'
Mysql
SHOW COLUMNS FROM a_table_named_users WHERE Field REGEXP 'user_id|user_name|user_pass'
This will return a result something like this:
Field | Type | Null | Key | Default | Extra
user_id int(8) NO PRI NULL auto_increment
user_name varchar(64) NO MUL NULL
user_pass varchar(64) NO NULL
Then to pull out the values you can simply
fetch row[0]
This is also great for passing input dynamically since the REGEXP needs the '|' for multiple inputs, but is also a way to keeps data separated and easy to store/pass to classes/functions.
Try throwing in dummy data as well for security when sending it out and compare what was returned when receiving any errors.
In Oracle, there is two views that describe columns:
DBA_TAB_COLUMNS describes the columns of all tables, views, and
clusters in the database.
USER_TAB_COLUMNS describes the columns of the tables, views, and
clusters owned by the current user. This view does not display the
OWNER column.
The answer is here: http://php.net/manual/en/function.mysql-list-fields.php
I'd use the following code in your case:
$result = mysql_query("SHOW COLUMNS FROM sometable");
if (!$result) {
echo 'Could not run query: ' . mysql_error();
exit;
}
$fields = array();
if (mysql_num_rows($result) > 0) {
while ($row = mysql_fetch_assoc($result)) {
$fields[] = $row['Field'];
}
}
you can run this query
SELECT t.name AS table_name,
SCHEMA_NAME(schema_id) AS schema_name,
c.name AS column_name
FROM sys.tables AS t
INNER JOIN sys.columns c ON t.OBJECT_ID = c.OBJECT_ID
WHERE c.name LIKE '%%' --if you want to find specific column write here
ORDER BY schema_name, table_name;
Try this
select * from sys.all_columns c join sys.objects o on c.object_id=o.object_id where o.name = 'TABLENAME' and c.name like '%COLUMN NAME%'
Just select first row from the table , for oracle : select * from <table name> where rownum = 1;
Came across this question looking for access to column names on Teradata, so I'll add the answer for their 'flavour' of SQL:
SELECT ColumnName
FROM DBC.Columns
WHERE DatabaseName='DBASE_NAME'
AND TableName='TABLE_NAME';
The info is stored in the DBC dbase.
Getting data types is a little bit more involved:
Get column type using teradata system tables
I did it like this
SELECT
TOP 0
*
FROM
Posts
It works even in http://data.stackexchange.com whose service tables I am not aware of!
SELECT COLUMN_NAME
FROM YourDatabase.INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = 'YourTableName'