oracle用sql查询描述表结构及字段和说明
oracle用sql查询描述表结构及字段和说明 Oracle SELECT DISTINCT AAA.COLUMN_NAME,AAA.DATA_TYPE,AAA.DATA_LENGTH,AAA.NULLABLE,BBB.COMMENTS FROM ALL_TAB_COLUMNS AAA,USER_COL_COMMENTS BBB WHERE AAA.COLUMN_NAME=BBB.COLUMN_NAMEAND AAA.TABLE_NAME='SY_
oracle用sql查询描述表结构及字段和说明Oracle
SELECT DISTINCT AAA.COLUMN_NAME,AAA.DATA_TYPE,AAA.DATA_LENGTH,AAA.NULLABLE,BBB.COMMENTS FROM ALL_TAB_COLUMNS AAA,USER_COL_COMMENTS BBB WHERE AAA.COLUMN_NAME=BBB.COLUMN_NAME AND AAA.TABLE_NAME='SY_USER_JOB';
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How to check tablespace size of oracle
Apr 11, 2025 pm 08:15 PM
To query the Oracle tablespace size, follow the following steps: Determine the tablespace name by running the query: SELECT tablespace_name FROM dba_tablespaces; Query the tablespace size by running the query: SELECT sum(bytes) AS total_size, sum(bytes_free) AS available_space, sum(bytes) - sum(bytes_free) AS used_space FROM dba_data_files WHERE tablespace_
How to import oracle database
Apr 11, 2025 pm 08:06 PM
Data import method: 1. Use the SQLLoader utility: prepare data files, create control files, and run SQLLoader; 2. Use the IMP/EXP tool: export data, import data. Tip: 1. Recommended SQL*Loader for big data sets; 2. The target table should exist and the column definition matches; 3. After importing, data integrity needs to be verified.
How to uninstall Oracle installation failed
Apr 11, 2025 pm 08:24 PM
Uninstall method for Oracle installation failure: Close Oracle service, delete Oracle program files and registry keys, uninstall Oracle environment variables, and restart the computer. If the uninstall fails, you can uninstall manually using the Oracle Universal Uninstall Tool.
How to add table fields to oracle
Apr 11, 2025 pm 07:30 PM
Use the ALTER TABLE statement, the specific syntax is as follows: ALTER TABLE table_name ADD column_name data_type [constraint-clause]. Where: table_name is the table name, column_name is the field name, data_type is the data type, and constraint-clause is an optional constraint. Example: ALTER TABLE employees ADD email VARCHAR2(100) Add an email field to the employees table.
How to re-query oracle
Apr 11, 2025 pm 07:33 PM
Oracle provides multiple deduplication query methods: The DISTINCT keyword returns a unique value for each column. The GROUP BY clause groups the results and returns a non-repetitive value for each group. The UNIQUE keyword is used to create an index containing only unique rows, and querying the index will automatically deduplicate. The ROW_NUMBER() function assigns unique numbers and filters out results that contain only line 1. The MIN() or MAX() function returns non-repetitive values of a numeric column. The INTERSECT operator returns the common values of the two result sets (no duplicates).
How to create a table in oracle
Apr 11, 2025 pm 08:00 PM
Creating an Oracle table involves the following steps: Use the CREATE TABLE syntax to specify table names, column names, data types, constraints, and default values. The table name should be concise and descriptive, and should not exceed 30 characters. The column name should be descriptive, and the data type specifies the data type stored in the column. The NOT NULL constraint ensures that null values are not allowed in the column, and the DEFAULT clause specifies the default values for the column. PRIMARY KEY Constraints to identify the unique record of the table. FOREIGN KEY constraint specifies that the column in the table refers to the primary key in another table. See the creation of the sample table students, which contains primary keys, unique constraints, and default values.
How to encrypt oracle view
Apr 11, 2025 pm 08:30 PM
Oracle View Encryption allows you to encrypt data in the view, thereby enhancing the security of sensitive information. The steps include: 1) creating the master encryption key (MEk); 2) creating an encrypted view, specifying the view and MEk to be encrypted; 3) authorizing users to access the encrypted view. How encrypted views work: When a user querys for an encrypted view, Oracle uses MEk to decrypt data, ensuring that only authorized users can access readable data.
How to solve garbled code in oracle
Apr 11, 2025 pm 10:09 PM
Oracle garbled problems can be solved by checking the database character set to ensure they match the data. Set the client character set to match the database. Convert data or modify column character sets to match database character sets. Use Unicode character sets and avoid multibyte character sets. Check that the language settings of the database and client are correct.
