The following query on the standard view user_tab_col:
select * from user_tab_cols;
returns on Oracle the columns column_name and qualified_col_name.
What is the difference?
qualified_col_name indicates full column path for XML tables. Basically it stores the expression for this column. For regular columns it will be equal to column_name.
If you run:
select owner, table_name, column_name, data_type, qualified_col_name
from all_tab_cols
where column_name <> qualified_col_name;
you will see returned columns from XML tables in XDB schema.
For example:
OWNER TABLE_NAME COLUMN_NAME DATA_TYPE QUALIFIED_COL_NAME
XDB XDB$SIMPLE_TYPE SYS_NC00074$ XDB$APPINFO_LIST_T "XMLDATA"."RESTRICTION"."MIN_INCLUSIVE"."ANNOTATION"."APPINFO"
Update:
For object tables qualified_col_name stores expression of type casting and accessing to attribute. For example:
create or replace type test1_obj as object(
n1 number,
n2 number,
s1 varchar2(10),
s2 varchar2(20)
)
not final;
create or replace type test2_obj under test1_obj(
d1 date,
d2 date
)
not final;
create table object_table of test1_obj;
select column_name, data_type, qualified_col_name
from user_tab_cols
where table_name = 'OBJECT_TABLE'
order by internal_column_id;
For last 2 hidden system columns reserved for instances of type test2_obj we can see:
COLUMN_NAME DATA_TYPE QUALIFIED_COL_NAME
SYS_NC00010$ DATE TREAT(SYS_NC_ROWINFO$ AS "TEST"."TEST2_OBJ")."D1"
SYS_NC00011$ DATE TREAT(SYS_NC_ROWINFO$ AS "TEST"."TEST2_OBJ")."D2"
Related
I want a query in oracle to get the column name from the table by passing value.
Means that In most of the case - We write the query like that - select * from table where column = 'value'. But in my case i don't know the column name.
Can any one suggest me.
Thanks in advance...
You can try to build a dynamic query to check all the tables of your DB.
setup:
create table tab1 ( v1 varchar2(100), n1 number, v1b varchar2(100));
create table tab2 ( v2 varchar2(100), n2 number, v2b varchar2(100));
create table tab3 ( v3 varchar2(100), n3 number, v3b varchar2(100));
insert into tab1 values ('Maria', 1, 'aa');
insert into tab1 values ('xx', 2, 'bb');
insert into tab2 values ('yy', 3, 'Maria');
insert into tab2 values ('zz', 3, 'cc');
insert into tab3 values ('WW', 4, 'DD');
build the dynamic query:
select 'select table_name,
matches from (' || listagg(statement, ' UNION ALL ') within group (order by table_name) || ')
where matches > 0'
from (
select 'select ''' || table_name ||
''' as TABLE_NAME, count(1) as MATCHES from ' || table_name || ' WHERE ' ||
listagg(column_name || ' = ''Maria''', ' OR ') within group (order by column_name) as statement,
table_name
from user_tab_columns col
where data_type = 'VARCHAR2'
group by table_name
)
This will return a query, that you can run to check all the tables; in my example, this will build the query (not formatted) :
SELECT table_name, matches
FROM (SELECT 'TAB1' AS TABLE_NAME, COUNT(1) AS MATCHES
FROM TAB1
WHERE V1 = 'Maria'
OR V1B = 'Maria'
UNION ALL
SELECT 'TAB2' AS TABLE_NAME, COUNT(1) AS MATCHES
FROM TAB2
WHERE V2 = 'Maria'
OR V2B = 'Maria'
UNION ALL
SELECT 'TAB3' AS TABLE_NAME, COUNT(1) AS MATCHES
FROM TAB3
WHERE V3 = 'Maria'
OR V3B = 'Maria')
WHERE matches > 0;
Running this query will give:
TABL MATCHES
---- ----------
TAB1 1
TAB2 1
Please notice that I used USER_TAB_COLUMNS, thus searching only in the tables of the login schema; if you want to search in different schemas, you can use ALL_TAB_COLUMNS or DBA_TAB_COLUMNS, depending on what you need and on the privileges of you user; see here for something more.
Also, consider that USER_TAB_COLUMNS will get the colums of tables and views; if you want to limit your search to tables, you can join USER_TAB_COLUMNS(ALL_TAB_COLUMNS, DBA_TAB_COLUMNS) to USER_TABLES (ALL_TABLES, DBA_TABLES) by TABLE_NAME, or TABLE_NAME and OWNER If you decide to use ALL or DBA tables:
SQL> create view vTab1 as select * from tab1;
View created.
SQL> select count(1)
2 from user_tab_columns
3 where table_name = 'VTAB1';
COUNT(1)
----------
3
SQL> select count(1)
2 from user_tab_columns
3 inner join user_tables using(table_name)
4 where table_name = 'VTAB1';
COUNT(1)
----------
0
SQL>
select table_name from user_Tables where table_name = 'bogus';
The following mysql query returns the constraints and the default values along with column_name, is_null and other details -
mysql query - select TABLE_NAME, COLUMN_NAME, COLUMN_DEFAULT, IS_NULLABLE, COLUMN_TYPE, COLUMN_KEY, EXTRA from INFORMATION_SCHEMA.COLUMNS where TABLE_SCHEMA = 'DB_NAME'
I want to write a similar query in Oracle, the following query returns data_type and is_null but doesn't return constraints and default values -
Oracle query - SELECT TABLE_NAME, COLUMN_NAME, DATA_TYPE, NULLABLE FROM DBA_TAB_COLUMNS where owner = 'USERNAME'
How can I extract those information from an oracle table.
Note: I don't want to use describe table
Select tc.TABLE_NAME, tc.COLUMN_NAME, tc.DATA_TYPE, tc.NULLABLE, tc.DATA_DEFAULT,
con.cons
from DBA_TAB_COLUMNS tc
left join
( select listagg( cc.constraint_name, ',') within group (order by cc.constraint_name) cons,
table_name, owner , column_name
from DBA_CONS_COLUMNS cc
group by table_name, owner , column_name ) con
on con.table_name = tc.table_name and
con.owner = tc.owner and
con.column_name = tc.column_name
where tc.owner = 'USERNAME'
order by 1 ,2
There can be multiple constraints (or none) for each column. Because of that left join is used and listagg function to display all constraint in one column.
TABLE_NAME COLUMN_NAME DATA_TYPE NULLABLE DATA_DEFAULT CONS
AQ$_QUEUE_TABLES OBJNO NUMBER N AQ$_QUEUE_TABLES_PRIMARY,SYS_C001643
AQ$_QUEUE_TABLES SCHEMA VARCHAR2 N SYS_C001640
AQ$_QUEUE_TABLES SORT_COLS NUMBER N SYS_C001645
AQ$_QUEUE_TABLES TABLE_COMMENT VARCHAR2 Y
AQ$_QUEUE_TABLES TIMEZONE VARCHAR2 Y
You can still try to use this below snippet to get the requested details. Hope this helps.
Note : This is for indexed columns as I thought you might need this too
SELECT DISTINCT col.owner,
col.table_name,
col.DATA_TYPE,
Col.Column_Name,
DECODE(nullable,'Y','Yes','N','No') nullable,
high_value(col.table_name,col.column_name), -- This is own created function to deal with LONG datatype columns
Ind.Index_Name
FROM SYS.All_Tab_Cols col,
All_Ind_Columns ind
WHERE Col.Table_Name = Ind.Table_Name
AND Col.Column_Name = Ind.Column_Name(+)
AND Col.Table_Name = UPPER('<TABLE_NAME>')
AND Col.Owner = '<SCHEMA_NAME>';
I crafted the following PLSQL-statement and pass it to SqlPlus in Oracle (11g)
as normal user, to find out which column names in all_user_tables (I'm actually only interested on those tables that are created by the schema owner) are of type LONG VARCHAR
select table_name, column_name from all_tab_columns where data_type='LONG VARCHAR';
The result is
no rows selected
but I'm sure that I have made use of LONG VARCHAR in a couple of places in tables. Somehow I'm using the wrong table to search or some other logic is wrong.
try this
select table_name, column_name, data_type
from all_tab_columns
where data_type IN('LONG','VARCHAR2');
Or this
SELECT *
FROM DBA_TAB_COLUMNS
where data_type IN('LONG','VARCHAR2')
and owner in 'YOUR_SCHEMA';
Why an entry is created in user_tab_cols when we create a function based on a column of a table?
create table t1(a varchar2(100), b number);
select * from user_tab_cols where table_name = 'T1'; -- Two rows coming
create index idx1 on t1(upper(a));
select * from user_tab_cols where table_name = 'T1'; -- Three rows coming
What is the reason to put an entry in user_tab_cols?
The extra column is a virtual column that Oracle has added to store the value of the indexed expression. From the Oracle documentation:
Oracle Database represents the index expression as a virtual column
You can easily verify in SQL*Plus that the extra column is virtual. In fact, it is also a 'hidden' column:
SQL> select column_name, hidden_column, virtual_column from user_tab_cols where table_name = 'T1';
COLUMN_NAME HID VIR
------------------------------ --- ---
A NO NO
B NO NO
SYS_NC00003$ YES YES
The name of the virtual column may be different on your machine.
user_tab_columns filters out hidden columns, as explained in the Oracle documentation for user_tab_cols. So, if you don't wish to see this column, you can query user_tab_columns instead of user_tab_cols:
SQL> select column_name from user_tab_columns where table_name = 'T1';
COLUMN_NAME
------------------------------
A
B
SQL>
I have around 1000 table out of which I need to list out the table names having clob or blob or lob containing columns. Is there any query to list out the same from my schema?
Try like this,
SELECT DISTINCT table_name
FROM user_tab_cols
WHERE data_Type IN ('CLOB', 'LOB', 'BLOB');
Try this one:
SELECT OWNER, TABLE_NAME, COLUMN_NAME, DATA_TYPE
FROM ALL_TAB_COLUMNS
WHERE DATA_TYPE IN ('CLOB', 'BLOB');
I havent a database handy, but this should work:
select * from ALL_TAB_COLUMNS a where a.DATA_TYPE in ('CLOB','BLOB','NCLOB','BFILE');
(see: http://docs.oracle.com/cd/B19306_01/server.102/b14237/statviews_2094.htm and http://docs.oracle.com/cd/B19306_01/server.102/b14200/sql_elements001.htm)