The binary string mode is displayed after the value with the field type of longtext in MySQL is exported

Catalog

MySQL Field type is longtext The binary string is displayed after the value of is exported

Use MySQL Of CAST() Function or CONVERT() function

MySQL Basic sentences and usage of

WHERE Clause ： Condition search

UPDATE Clause ： Data update

DELETE Clause ： Delete data

LINK Clause ： Metacharacter lookup

UNION The operator ： Joint query results

MySQL Field type is longtext The binary string is displayed after the value of is exported

MySQL The field type in is longtext The field value of is saved as Blob (Binary large objects), So export sql Or will sql When querying data exported to other formats , You need to convert the field type in advance , Conversion mode ：

Use MySQL Of CAST() Function or CONVERT() function

grammar ：

CAST(value as type);CONVERT(value, type);

Example ：

SELECT    CAST(t.longtextField AS CHAR) AS longtextFieldFROM    tableName t;SELECT    CONVERT(t.longtextField, CHAR) AS longtextFieldFROM    tableName t;MySQL Basic sentences and usage of WHERE Clause ： Condition search SELECT Column name ·· FROM The name of the table ·· WHERE Conditions （AND）（OR）

explain ： 

You can use one or more tables in a query statement , Use commas between tables , Division , And use WHERE Statement to set the query conditions .

You can WHERE Clause to specify any condition .

You can use AND perhaps OR Specify one or more conditions .

Be careful ： if WHERE add BINARY, Then the field value will be case sensitive .

UPDATE Clause ： Data update UPDATE The name of the table SET Column name = The new value WHERE Column name = Certain value

explain ：

Choose to update multiple fields at the same time .

stay WHERE Post specified condition .

DELETE Clause ： Delete data DELETE FROM The name of the table WHERE Column name = value

explain ：

If not specified WHERE Clause ,MySQL All records in the table will be deleted .

You can WHERE Clause to specify any condition

You can delete records once in a single table .

LINK Clause ： Metacharacter lookup SELECT Column name  FROM table_nameWHERE field1 LIKE condition1 [AND [OR]] filed2 = 'somevalue'

explain ：

stay WHERE Clause to specify any condition .

stay WHERE Used in clauses LIKE Clause .

You can use LIKE Clause instead of equal sign =.

LIKE Usually with % Use together , Similar to a metacharacter search .

You can use AND perhaps OR Specify one or more conditions .

You can DELETE or UPDATE Use in command WHERE...LIKE Clause to specify the condition .

'%a'     // With a Data at the end 'a%'     // With a Initial data '%a%'    // contain a The data of '_a_'    // Three and the middle letter is a Of '_a'     // Two characters and the ending letter is a Of 'a_'     // It's two and starts with a Of UNION The operator ： Joint query results SELECT Column name FROM tables[WHERE conditions]UNION [ALL | DISTINCT]SELECT Column name FROM tables[WHERE conditions];

explain ：

expression1, expression2, ... expression_n: Columns to retrieve .

tables: Data table to retrieve .

WHERE conditions: Optional , Retrieve conditions .

DISTINCT: Optional , Delete duplicate data in result set . By default UNION The operator has removed the duplicate data , therefore DISTINCT Modifiers have little effect on the results .

ALL: Optional , Return all result sets , Contains duplicate data .

The above is personal experience , I hope I can give you a reference , I also hope you can support the software development network .