I am setting a variable, and then I want to use the USE command to change the database. Unfortunately USE doesn't evaluate the variable.
SET #con="testDB";
Query OK, 0 rows affected (0.00 sec)
select #con;
+--------+
| #con |
+--------+
| testDB |
+--------+
1 row in set (0.00 sec)
use #con;
ERROR 1049 (42000): Unknown database '#con'
So the value of the variable is not evaluated when I try to connect. Any ideas?
I have found my own solution, so I am going to answer my own question, in case anybody is interested.
#outis you are right, it's not possible to use a variable with the command USE.
However, due to the fact that I want to create a table in a database specified at runtime, my solution would be to use dynamic SQL:
set #schema="testDB";
set #front="CREATE TABLE IF NOT EXISTS ";
set #endpart=".`TEST1` (DIM_ID INT(16)) ENGINE = InnoDB DEFAULT CHARACTER SET = utf8 COLLATE = utf8_unicode_ci;";
set #stat=concat(#front,#schema,#endpart);
prepare command from #stat;
execute command;
So basically this solution builds up the statement, prepares it and executes it.
#schema parameter can even be past down to the script. This way I dynamically build the create statement.
I don't think it's possible to USE #var; in some way. But in some cases doing it the other way around might be an option.
USE testDB;
SET #schema = DATABASE();
Related
I have table with:
1) Encrypted_ID varchar (256)
2) Initialization Vector(iv)varchar(256).
I would like to decrypt the column value using the key
I am using:
select Cast(AES_DECRYPT(Encrypted_ID,'Key',InitializationVector_iv)as CHAR ) as DecryptedValue from MyTable;
The result is Null.
I Also tried:
select Cast(AES_DECRYPT(AES_ENCRYPT(Encrypted_ID,'Key',InitializationVector_iv),'Key') as CHAR ) as DecryptedValue from MyTable;
The result is blob for few rows.
I'm not sure what I'm doing wrong here. Can any one help with the syntax to decrypt the column when I have:
Key
Initialization Vector value
Encrypted Column
There's actually nothing wrong with your first query, syntactically it's spot on as this worked example demonstrates.
mysql> SET ##SESSION.block_encryption_mode = 'aes-256-cbc';
mysql> create table MyTable(
-> Encrypted_ID varbinary(256),
-> InitializationVector_iv varbinary(16)
-> );
Query OK, 0 rows affected (0.93 sec)
mysql> SET #iv = RANDOM_BYTES(16);
Query OK, 0 rows affected (0.00 sec)
mysql> INSERT INTO MyTable SET Encrypted_ID = AES_ENCRYPT('hello','key', #iv), InitializationVector_iv = #iv;
Query OK, 1 row affected (0.17 sec)
mysql> SELECT CAST(AES_DECRYPT(Encrypted_ID,'key', InitializationVector_iv) AS CHAR) from MyTable;
+------------------------------------------------------------------------+
| CAST(AES_DECRYPT(Encrypted_ID,'key', InitializationVector_iv) AS CHAR) |
+------------------------------------------------------------------------+
| hello |
+------------------------------------------------------------------------+
1 row in set (0.00 sec)
As for why it's not working, I managed to get the query to return NULL in 2 scenarios. One, you get NULL returned if you use a different iv for encryption and decryption, so you might want to look at how you are storing as the iv. Two, you get NULL where you have the block_encryption_mode variable set differently when storing and trying to retrieve the value, check that you're not accidentally reverting to the default 'aes-128-ebc between sessions. There may be others...
The second query will fail because you need to supply the iv to both of he encryption and decryption functions, you only use it to encrypt. Also, since you are taking the values from the MyTable, Encrypted_ID will already be encrypted and the effect of this query would be to encrypt it again, before reversing that to get you back to the stored (encrypted) value.
Finally, AES is only going to use 16 bytes of the iv so you might as well make that VARBINARY(16).
AES doesn't work with MySQL Workbench in my case.
I have to use the mysql console.
MySql Workbench worked for me.
In my Case, encrypted value was encoded in base 64.
So I had to decode base 64 value and IV Using "From_base64" function.
SET block_encryption_mode = 'aes-256-cbc';
set #k = 'Key';
set #iv = From_base64('InitializationVector');
set #v = from_base64('EncryptedValue');
select CAST(AES_DECRYPT(#v, #k, #iv) AS CHAR);
Please make sure the encryption type, base 64 encoding, Hex/Unhex of the values/Iv are correct before you start working on the decryption.
Review MYSql functions
https://dev.mysql.com/doc/refman/8.0/en/string-functions.html
Hope this helps for someone.
mysql> select * from users where id=0;
Empty set (0.00 sec)
mysql> select * from users where id=0 and sleep(5);
Empty set (0.00 sec)
mysql> select * from users where id=0 and benchmark(1000000,sha1(1));
Empty set (0.39 sec)
mysql> select * from users where id=0 xor sleep(5);
Empty set (1 min 5.02 sec)
when id=0, the user doesn't exist. why the second query doesn't sleep 5s? when I use benchmark（1000000,sha1(1)) or xor sleep(5), why it will sleep?
Thanks.
This is called "short-circuiting" and it is considered a feature of pretty much all databases -- and almost all programming languages.
Logic that does not need to be executed is not executed. It has nothing to do with sleep(). It is simply desirable to stop executing code when the engine already knows the answer.
I do not think that forcing a sleep() within a single query is a good idea. SQL Queries are not intended to be procedural. They describe the result set and the query engine generates the appropriate code. sleep() is not in the scope of SQL result sets.
I would recommend that -- if a sleep() really is necessary -- that you do it with a separate step in your scripts.
In MySQL, an overflow creates only a warning and MySQL destroys the data you feed it:
mysql> create table tmp(data tinyint primary key);
Query OK, 0 rows affected (7.83 sec)
mysql> insert into tmp set data = 200;
Query OK, 1 row affected, 1 warning (2.27 sec)
mysql> select * from tmp;
+------+
| data |
+------+
| 127 |
+------+
1 row in set (0.00 sec)
This is a huge problem, especially when using MySQL via a programming language, where one (usually) does not check any MySQL-warnings. This may cause not only data-corruption, but data-corruption that is hidden and may remain undetected - one of the worst things that may happen in a database.
Is there a way to configure MySQL so that an overflow causes an ERROR (similar to a syntax error) and not only a warning?
See Mysql documentation
you have to activate the strict SQL mode:
If strict SQL mode is enabled, MySQL rejects the out-of-range value with an error, and the insert fails, in accordance with the SQL standard.
If no restrictive modes are enabled, MySQL clips the value to the appropriate endpoint of the range and stores the resulting value instead.
I faced one issue when use mysql to create procedures.
I used "root#localhost" to create the procedure. the command executed successfully.
After that I remove procedure A and want to use "root#127.0.0.1" to create A and then faced the error: 1820 - You must SET PASSWORD before executing this statement.
Actually I have set the password for that, but still error.
And other procedure used "root#127.0.0.1" are all successfully without any error. The issue only faced on A.
As I know this error usually found on create DB. but this time... :(
Anybody can help me? Thanks very much!!!
Right from the manual:
After an account's password has been expired, all operations performed
in subsequent connections to the server using the account result in an
error until the user issues a SET PASSWORD statement to establish a
new account password:
mysql> SELECT 1;
ERROR 1820 (HY000): You must SET PASSWORD before executing this statement
mysql> SET PASSWORD = PASSWORD('new_password');
Query OK, 0 rows affected (0.01 sec)
mysql> SELECT 1;
+---+
| 1 |
+---+
| 1 |
+---+
1 row in set (0.00 sec)
Finally the issue was resolved with below statement:
++++++++++++++++++++++++++++++++++
SET PASSWORD FOR 'some_user'#'some_host' = PASSWORD('newpwd');
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Does anyone ever use MySQL spatial buffer function successfully?
I've read the documentation here: http://dev.mysql.com/doc/refman/5.0/en/functions-that-create-new-geometries-from-existing-ones.html#function_buffer
As stated in the documentation, buffer function has 2 parameters. The first one is geometry typed, the second one is distance.
I've try to make a geometry variable
mysql> set #g1 = geomfromtext('POINT(1 1)');
Query OK, 0 rows affected (0.00 sec)
Then, to ensure that my variable is correctly set, I perform a query. If the variable not correctly set, such a query will return NULL. In this case, it is confirmed that my variable is correctly set
mysql> select astext(#g1);
+-------------+
| astext(#g1) |
+-------------+
| POINT(1 1) |
+-------------+
1 row in set (0.00 sec)
I run a query to select a buffer as stated in documentation
mysql> select astext(buffer(#g1, 5));
ERROR 1305 (42000): FUNCTION module_devel.buffer does not exist
Do I miss something here?
EDIT Sorry guys, I think I miss this:
12.17.5.3.2. Spatial Operators
OpenGIS proposes a number of other functions that can produce
geometries. They are designed to implement spatial operators.
These functions are not implemented in MySQL.
This is related to this bug report maybe. Which MySQL server are you using? Maybe you should upgrade to 5.6.