I am tasked to export users from an old project to another database, however the table name is USER (I was not around when that choice was made.)
In databases like MySQL, I could do
SELECT * FROM `user`;
But that escape character is illegal in Oracle.
So, how can I write the above query in Oracle?
Use double-quotes, not backticks, as referenced in the documentation.
SELECT * FROM "user";
Depending on how it was created - and how it appears in the data dictionary, which you can check with select table_name from user_tables where lower(table_name) = 'user' (with single quotes because here it's a string literal not an identifier!) - you may need it to be mixed-case or uppercase:
SELECT * FROM "USER";
As that documentation says, unquoted names are not case-sensitive; but quoted names are. One of several reasons to avoid them if you can.
Related
I am trying to create an Oracle Spatial index but seeing strange behavior.
I have a table in my schema as follows:
CREATE TABLE "Event" (
"EventID" NUMBER(32,0) GENERATED ALWAYS AS IDENTITY INCREMENT BY 1 START WITH 1 NOT NULL,
"Name" NVARCHAR2(30),
"Location" "SDO_GEOMETRY" NOT NULL,
CONSTRAINT "PK_EVENT" PRIMARY KEY ("EventID")
) ;
This works fine and I know I have to create an entry in user_sdo_geom_metadata, that works as you would expect with the following:
insert into user_sdo_geom_metadata (table_name,column_name,diminfo,srid) values ('Event','Location',
sdo_dim_array(sdo_dim_element('X',-180.0,180.0, 0.005),sdo_dim_element('Y',-90.0,90.0, 0.005)), 4326);
This reports success and when I do a select on user_sdo_geom_metadata I see the row. However, when I try to create the spatial index with:
CREATE INDEX "EVINDEX" ON "Event" ("Location") INDEXTYPE IS MDSYS.SPATIAL_INDEX_V2
I get the following error:
SQL Error [29855] [99999]: ORA-29855: error occurred in the execution of ODCIINDEXCREATE routine
ORA-13203: failed to read USER_SDO_GEOM_METADATA view
ORA-13203: failed to read USER_SDO_GEOM_METADATA view
ORA-06512: at "MDSYS.SDO_INDEX_METHOD_10I", line 10
The weird thing is the Index looks like it's been created.
select * from all_indexes where table_name='Event';
Shows the index??? The other odd thing is when I do a select * on ALL_SDO_GEOM_METADATA, no rows are returned??? I'm connecting as a user with almost every privilege and role but not as SYSDBA. I can't get my head around this one.
UPDATE
Incredibly, this seems to be a case sensitivity issue. If you change the table and column names to all UPPERCASE it works. It seems my neverending disappointment in Oracle has a whole new chapter. Going to try to struggle through this somehow, but like most things with Oracle, it's one unrelenting slog to get anything done :(
The documentation says:
The table name cannot contain spaces or mixed-case letters in a quoted string when inserted into the USER_SDO_GEOM_METADATA view, and it cannot be in a quoted string when used in a query (unless it is in all uppercase characters).
and
The column name cannot contain spaces or mixed-case letters in a quoted string when inserted into the USER_SDO_GEOM_METADATA view, and it cannot be in a quoted string when used in a query (unless it is in all uppercase characters).
However, it also says:
All letters in the names are converted to uppercase before the names are stored in geometry metadata views or before the tables are accessed. This conversion also applies to any schema name specified with the table name.
which you can see if you query the user_sdo_geom_metadata view after your insert; the mixed-case names have become uppercase EVENT and LOCATION.
But then:
Note: Letter case conversion does not apply if you use mixed case (“CamelCase”) names enclosed in quotation marks. However, be aware that many experts recommend against using mixed-case names.
And indeed, rather unintuitively, it seems to work if you include the quotes in the user_sdo_geom_metadata insert:
insert into user_sdo_geom_metadata (table_name,column_name,diminfo,srid)
values (
'"Event"',
'"Location"',
sdo_dim_array(sdo_dim_element('X',-180.0,180.0, 0.005),
sdo_dim_element('Y',-90.0,90.0, 0.005)), 4326
);
db<>fiddle
So it appears that the values from the view are at some point concatenated into a dynamic SQL statement, which would explain some of the behaviour.
One of my columns is called from. I can't change the name because I didn't make it.
Am I allowed to do something like SELECT from FROM TableName or is there a special syntax to avoid the SQL Server being confused?
Wrap the column name in brackets like so, from becomes [from].
select [from] from table;
It is also possible to use the following (useful when querying multiple tables):
select table.[from] from table;
If it had been in PostgreSQL, use double quotes around the name, like:
select "from" from "table";
Note: Internally PostgreSQL automatically converts all unquoted commands and parameters to lower case. That have the effect that commands and identifiers aren't case sensitive. sEleCt * from tAblE; is interpreted as select * from table;. However, parameters inside double quotes are used as is, and therefore ARE case sensitive: select * from "table"; and select * from "Table"; gets the result from two different tables.
These are the two ways to do it:
Use back quote as here:
SELECT `from` FROM TableName
You can mention with table name as:
SELECT TableName.from FROM TableName
While you are doing it - alias it as something else (or better yet, use a view or an SP and deprecate the old direct access method).
SELECT [from] AS TransferFrom -- Or something else more suitable
FROM TableName
Your question seems to be well answered here, but I just want to add one more comment to this subject.
Those designing the database should be well aware of the reserved keywords and avoid using them. If you discover someone using it, inform them about it (in a polite way). The keyword here is reserved word.
More information:
"Reserved keywords should not be used
as object names. Databases upgraded
from earlier versions of SQL Server
may contain identifiers that include
words not reserved in the earlier
version, but that are reserved words
for the current version of SQL Server.
You can refer to the object by using
delimited identifiers until the name
can be changed."
http://msdn.microsoft.com/en-us/library/ms176027.aspx
and
"If your database does contain names
that match reserved keywords, you must
use delimited identifiers when you
refer to those objects. For more
information, see Identifiers (DMX)."
http://msdn.microsoft.com/en-us/library/ms132178.aspx
In Apache Drill, use backquotes:
select `from` from table;
If you ARE using SQL Server, you can just simply wrap the square brackets around the column or table name.
select [select]
from [table]
I have also faced this issue.
And the solution for this is to put [Column_Name] like this in the query.
string query= "Select [Name],[Email] from Person";
So it will work perfectly well.
Hi I work on Teradata systems that is completely ANSI compliant. Use double quotes " " to name such columns.
E.g. type is a SQL reserved keyword, and when used within quotes, type is treated as a user specified name.
See below code example:
CREATE TABLE alpha1
AS
(
SEL
product1
type_of_product AS "type"
FROM beta1
) WITH DATA
PRIMARY INDEX (product1)
--type is a SQL reserved keyword
TYPE
--see? now to retrieve the column you would use:
SEL "type" FROM alpha1
I ran in the same issue when trying to update a column which name was a keyword. The solution above didn't help me. I solved it out by simply specifying the name of the table like this:
UPDATE `survey`
SET survey.values='yes,no'
WHERE (question='Did you agree?')
The following will work perfectly:
SELECT DISTINCT table.from AS a FROM table
Some solid answers—but the most-upvoted one is parochial, only dealing with SQL Server. In summary:
If you have source control, the best solution is to stick to the rules, and avoid using reserved words. This list has been around for ages, and covers most of the peculiarities. One tip is that reserved words are rarely plural—so you're usually safe using plural names. Exceptions are DIAGNOSTICS, SCHEMAS, OCTETS, OFFSETS, OPTIONS, VALUES, PARAMETERS, PRIVILEGES and also verb-like words that also appear plural: OVERLAPS, READS, RETURNS, TRANSFORMS.
Many of us don't have the luxury of changing the field names. There, you'll need to know the details of the RDBM you're accessing:
For SQL Server use [square_braces] around the name. This works in an ODBC connection too.
For MySQL use `back_ticks`.
Postgres, Oracle and several other RDBMs will apparently allow "double_quotes" to be used.
Dotting the offending word onto the table name may also work.
You can put your column name in bracket like:
Select [from] from < ur_tablename>
Or
Put in a temprary table then use as you like.
Example:
Declare #temp_table table(temp_from varchar(max))
Insert into #temp_table
Select * from your_tablename
Here I just assume that your_tablename contains only one column (i.e. from).
In MySQL, alternatively to using back quotes (`), you can use the UI to alter column names. Right click the table > Alter table > Edit the column name that contains sql keyword > Commit.
select [from] from <table>
As a note, the above does not work in MySQL
Judging from the answers here and my own experience. The only acceptable answer, if you're planning on being portable is don't use SQL keywords for table, column, or other names.
All these answers work in the various databases but apparently a lot don't support the ANSI solution.
Simple solution
Lets say the column name is from ; So the column name in query can be referred by table alias
Select * from user u where u.from="US"
In Oracle SQL Developer, pl/sql you can do this with double quotes but if you use double quotes you must type the column names in upper case. For example, SELECT "FROM" FROM MY_TABLE
This question already has answers here:
What exactly do quotation marks around the table name do?
(2 answers)
Closed 8 years ago.
I've got a question. Why does my Oracle Express Edition requires double-quoted table names:
Not working select:
select * from table
Working select:
select * from "table"
Thanks for answers and help with editing my post. I was confused how to name this case.
It requires double quote names only in case the name you are using is a keyword (and your example - table is in this situation) or if you want to include special characters or non-alphanumeric characters (e.g. "Multi word table name").
The names enclosed in " are case sensitive.
Use doublequotes only:
select * from "table";
it works without quotes only of name was created is in uppercase. By default all unquoted names are stored in uppercase.
For example:
CREATE TABLE "T1" (x number);
-- That works:
select * from "T1";
-- that works too:
select * from t1;
-- that works too:
select * from T1;
TABLE - is a keyword. So you can it use without quotes even if you used name in uppercase in create statement:
CREATE TABLE "TABLE" (x number);
select * from table;
ORA-00906: missing left parenthesis
I have a schema in which a small number of the thousands of stored procedures have been created with quoted identifiers. I need to fix them. The only way I currently have of identifying them is by opening them up in SQLDeveloper, one at a time, and checking to see if the CREATE OR REPLACE... bit at the top has quotes around the procedure name. Does anyone have any cunning method of identifying these troublesome objects more easily? Have I overlooked some Oracle system view with a this_uses_quoted_identifiers flag, perhaps? Please enlighten me!
There are at least 2 ways:
select * from all_source where type = 'PROCEDURE' and line = 1 and text like '%"%'
and
select * from all_procedures where procedure_name != upper(procedure_name)
However, none of them is 100% correct and complete. The first one looks for any double quote in the first line. The second one would only find procedures with lower caps in their name which would mean that double quotes have been used.
As far as I know, if you quote an identifier, but all the letters are in capital form, it is just equivalent to non quoted identifier.
So you can select from ALL_OBJECTS to see which object names have names with non capital letters.
I have a little silly question. I have installed a PostgreSQL DB Server, but when I run query, there is a problem with column identifier without quotes. I don't know why the quotes around identifiers are needed. My query:
SELECT vc."CAR_ID"
FROM "VEL_CAR" vc, "VEL_DRIVER" vd, "VEL_DRIVER_CAR" vdc
WHERE vc."CAR_ID" = vdc."CAR_ID" and
vdc."DRIVER_ID" = vd."DRIVER_ID";
My practice from Oracle DB is not to use ". So in Oracle:
SELECT vc.CAR_ID
FROM VEL_CAR vc, VEL_DRIVER vd, VEL_DRIVER_CAR vdc
WHERE vc.CAR_ID = vdc.CAR_ID and
vdc.DRIVER_ID = vd.DRIVER_ID;
When I run this query without quotes in PostgreSQL it throws error about syntax:
ERROR: column vc.car_id does not exist
LINE 1: SELECT vc.CAR_ID
Do you know why?
--SOLVED--
Thank you, now I solved the problem! It was about table creation. I created table objects using pgAdminIII and i wrote table name and column names uppercased. pgAdminIII created query with quotas - because of the names was uppercased. So query had to be written with quotas.
When you create your tables using double quotes, column and table names become case sensitive. So "car_id" is a different name than "CAR_ID"
You need to create your tables without using double quotes, then the names are not case sensitive: car_id is the same as CAR_ID (note the missing quotes!)
See the manual for details:
http://www.postgresql.org/docs/current/static/sql-syntax-lexical.html#SQL-SYNTAX-IDENTIFIERS
Edit:
Oracle behaves just the same way. The only difference is that Oracle stores names in upper case and Postgres stores them in lower case. But the behaviour when using quotes is identical.
From Postgres documentation :
Quoting an identifier also makes it case-sensitive, whereas unquoted names are always folded to lower case. For example, the identifiers FOO, foo, and "foo" are considered the same by PostgreSQL, but "Foo" and "FOO" are different from these three and each other. (The folding of unquoted names to lower case in PostgreSQL is incompatible with the SQL standard, which says that unquoted names should be folded to upper case. Thus, foo should be equivalent to "FOO" not "foo" according to the standard. If you want to write portable applications you are advised to always quote a particular name or never quote it.)
Seems to me that the table vc does not have a column named car_id. Are you sure it is there? Do \d vel_car to see the structure of the table.
The quotes are optional and you can usually skip them.