The difference between MySQL and Oracle

1. Oracle is a large database and MySQL is a small and medium-sized database, Oracle has a market share of only about 20% 40%,mysql, while MySQL is open source and Oracle is very expensive.

2. Oracle supports high concurrency, large traffic, and is the best tool for OLTP. 3. The space used to install the difference is also very large, MySQL installed after the 152M and Oracle has about 3G, and the use of Oracle occupies a particularly large memory space and other machine performance. 4.Oracle also some differences in MySQL operation ① primary key MySQL generally uses the auto-grow type, when the table is created as long as the primary key of the specified table is auto increment, when inserting a record, you do not need to specify the primary key value of the record, MySQL will automatically grow Oracle does not have an autogrow type, a sequence used by the primary key, and the next value of the sequence number is paid to the field when the record is inserted; only the ORM framework is the native primary key generation strategy. ② Single-quote processing in MySQL you can use double quotes to wrap strings, and Oracle can only wrap strings with single quotes. Single quotation marks must be replaced before inserting and modifying strings: Replace all occurrences of a single quotation mark with two single quotes. ③ the processing of the SQL statement of the page turn the SQL statement of the page is simpler, with the limit starting position, the number of records; Oracle's SQL statement for paging is cumbersome. Each result set has only one rownum field indicating its location and can only be used with rownum<100, which cannot handle long strings with Rownum>80④ long strings Oracle also has its special place. Insert and update when the maximum operand length is less than or equal to 4,000 single bytes, if you want to insert a longer string, consider the field with the Clob type, the method borrows the Dbms_lob package from the Oracle. Be sure to do non-null and length judgments before inserting a modified record, and the field values that cannot be empty and the value beyond the length field should be warned to return the last action. ⑤ NULL character processing the non-empty fields of MySQL also have empty content, and Oracle defines non-empty fields that do not allow empty content. The Oracle table structure is defined by not NULL for MySQL, and errors are generated when the data is being directed. As a result, null characters are judged on the data, and if NULL or NULL, it is necessary to change it to a space string. Fuzzy comparison of ⑥ strings MySQL uses the field name like '% string% ', Oracle can also use the field name as '% string% ' but this method cannot use the index, the speed is not fast. ⑦oracle implements most of the functions in Ansii SQL, such as the isolation level of transactions, propagation characteristics, and so on, and MySQL is still relatively

The difference between MySQL and Oracle