问题
What are the maximum length of a table name and column name in Oracle?
回答1:
In Oracle 12.2 and above the maximum object name length is 128 bytes.
In Oracle 12.1 and below the maximum object name length is 30 bytes.
回答2:
Teach a man to fish
Notice the data-type and size
>describe all_tab_columns
VIEW all_tab_columns
Name Null? Type
----------------------------------------- -------- ----------------------------
OWNER NOT NULL VARCHAR2(30)
TABLE_NAME NOT NULL VARCHAR2(30)
COLUMN_NAME NOT NULL VARCHAR2(30)
DATA_TYPE VARCHAR2(106)
DATA_TYPE_MOD VARCHAR2(3)
DATA_TYPE_OWNER VARCHAR2(30)
DATA_LENGTH NOT NULL NUMBER
DATA_PRECISION NUMBER
DATA_SCALE NUMBER
NULLABLE VARCHAR2(1)
COLUMN_ID NUMBER
DEFAULT_LENGTH NUMBER
DATA_DEFAULT LONG
NUM_DISTINCT NUMBER
LOW_VALUE RAW(32)
HIGH_VALUE RAW(32)
DENSITY NUMBER
NUM_NULLS NUMBER
NUM_BUCKETS NUMBER
LAST_ANALYZED DATE
SAMPLE_SIZE NUMBER
CHARACTER_SET_NAME VARCHAR2(44)
CHAR_COL_DECL_LENGTH NUMBER
GLOBAL_STATS VARCHAR2(3)
USER_STATS VARCHAR2(3)
AVG_COL_LEN NUMBER
CHAR_LENGTH NUMBER
CHAR_USED VARCHAR2(1)
V80_FMT_IMAGE VARCHAR2(3)
DATA_UPGRADED VARCHAR2(3)
HISTOGRAM VARCHAR2(15)
回答3:
DESCRIBE all_tab_columns
will show a TABLE_NAME VARCHAR2(30)
Note VARCHAR2(30) means a 30 byte limitation, not a 30 character limitation, and therefore may be different if your database is configured/setup to use a multibyte character set.
Mike
回答4:
Right, but as long as you use ASCII characters even a multibyte character set would still give a limitation of exactly 30 characters... so unless you want to put hearts and smiling cats in you're DB names your fine...
回答5:
30 char (bytes, really, as has been stated).
But do not trust me; try this for yourself:
SQL> create table I23456789012345678901234567890 (my_id number);
Table created.
SQL> create table I234567890123456789012345678901(my_id number);
ERROR at line 1:
ORA-00972: identifier is too long
Updated: as stated above, in Oracle 12.2 and later, the maximum object name length is now 128 bytes.
回答6:
The schema object naming rules may also be of some use:
http://download.oracle.com/docs/cd/B19306_01/server.102/b14200/sql_elements008.htm#sthref723
回答7:
On Oracle 12.2
, you can use built-in constant, ORA_MAX_NAME_LEN
,
set to 128 bytes (as per 12.2)
Prior to Oracle 12.1
max size was 30 bytes.
回答8:
In the 10g database I'm dealing with, I know table names are maxed at 30 characters. Couldn't tell you what the column name length is (but I know it's > 30).
回答9:
Oracle database object names maximum length is 30 bytes.
Object Name Rules: http://docs.oracle.com/database/121/SQLRF/sql_elements008.htm
回答10:
The maximum name size is 30 characters because of the data dictionary which allows the storage only for 30 bytes
回答11:
I'm working on Oracle 12c 12.1. However, doesn't seem like it allows more than 30 characters for column/table names.
Read through an oracle page which mentions 30 bytes. https://docs.oracle.com/database/121/SQLRF/sql_elements008.htm#SQLRF00223
In 12c although the all_tab_columns do say VARCHAR2(128) for Table_Name, it does not allow more than 30 bytes name.
Found another article about 12c R2, which seems to be allowing this up to 128 characters. https://community.oracle.com/ideas/3338
回答12:
The maximum length of the table and column name is 128 bytes or 128 characters. This limit is for using sybase database users. I verified this answer thoroughly, so that I have posted this answer confidently.
来源:https://stackoverflow.com/questions/756558/what-is-the-maximum-length-of-a-table-name-in-oracle