I'm doing a Java program that has to interact with a MySQL database, and I'm trying to delete a row of a table from a query in Java.
The problem is that when I try to convert a String in Java, "2021/2022" to char(9) I get an error that says that data is too long for column. Can anyone help?
This is the method that should delete the row:
public boolean borrarMatricula(Connection conn, int alumno, int profesor, int asignatura,
String c){
boolean borrado = false;
String drop = "DROP PROCEDURE IF EXISTS DELETE_ENROLLMENT";
String rutina = "CREATE PROCEDURE DELETE_ENROLLMENT(IN alumno double(4,0), "
+ "IN profesor double(2,0), IN asignatura double(3,0), IN c char(9))"
+ "BEGIN "
+ "DELETE FROM MATRICULAS WHERE codigoAlumno=alumno and "
+ "codigoProfesor=profesor and codigoAsignatura=asignatura and curso=c;"
+ "END";
try{
Statement s = conn.createStatement();
s.execute(drop);
s.execute(rutina);
CallableStatement cs=conn.prepareCall("{call DELETE_ENROLLMENT(" +
alumno + "," + profesor + "," + asignatura + "," + c + ")}");
cs.execute();
borrado = true;
}
catch(SQLException e){
Vista.muestraErrorSQL(e);
}
catch(Exception e){
e.printStackTrace(System.err);
}
return(borrado);
}
"Curso" is defined as a char(9), and the String I'm using is 2021/2022
What happened is that you are concatenating Java variables into your CALL statement:
CallableStatement cs=conn.prepareCall("{call DELETE_ENROLLMENT(" +
alumno + "," + profesor + "," + asignatura + "," + c + ")}");
So it runs a CALL statement as though you formatted it like this:
mysql> call delete_enrollment(1, 1, 1, 2021/2022);
Query OK, 0 rows affected, 1 warning (0.00 sec)
mysql> show warnings;
+---------+------+----------------------------------------+
| Level | Code | Message |
+---------+------+----------------------------------------+
| Warning | 1265 | Data truncated for column 'c' at row 1 |
+---------+------+----------------------------------------+
In Java, warnings are promoted to errors. The value is not the string '2021/2022', but a floating-point value which is the quotient of 2021/2022, or approximately 0.9995. It results in a warning when you try to use a floating-point value as a string.
If you used an actual quoted string, there is no warning:
mysql> call delete_enrollment(1, 1, 1, '2021/2022');
Query OK, 0 rows affected (0.00 sec)
But you should just avoid using string concatenation. You're already using a prepared statement, so you should use bound parameters:
CallableStatement cs=conn.prepareCall("{call DELETE_ENROLLMENT(?, ?, ?, ?)}");
cs.setDouble(1, alumno);
cs.setDouble(2, profesor);
cs.setDouble(3, asignatura);
cs.setString(4, c);
cs.execute();
Using parameters instead of string-concatenation is one of the most important reasons to use prepared statements. It makes your code more secure and less error-prone, and it's easier to read and write the code.
See also: https://dev.mysql.com/doc/connector-j/8.0/en/connector-j-usagenotes-statements-callable.html
Related
I am trying to insert data from ArrayLists into a mysql table in Java, however I keep getting the following error: java.sql.SQLException: Data truncated for column 'AAL' at row 1.
Here is some of the code:
stmt = conn.createStatement();
sql = "CREATE TABLE IF NOT EXISTS stocks "
+ "(id INTEGER not NULL AUTO_INCREMENT, date LONGBLOB , " + "time LONGBLOB, "
+ " PRIMARY KEY ( id ))";
stmt.executeUpdate(sql);
System.out.println("Created table in given database...");
for (int i = 0; i < stockList.size(); i++) {
System.out.println(stockList.get(i).getName() + i);
sql = "ALTER TABLE stocks ADD " + stockList.get(i).getName() + " DOUBLE";
stmt.executeUpdate(sql);
}
for (int i = 0; i < stockList.size(); i++) {
System.out.println(i);
sql = "INSERT INTO stocks (id, date, time, " + stockList.get(i).getName() + ") VALUES (NULL, '" + stockList.get(i).getDate() +
"', '" + stockList.get(i).getTime() + "', '" + stockList.get(i).getPrice() + "')";
stmt.executeUpdate(sql);
}
Any help is much appreciated.
You indicated that stockList.get(i).getPrice() is a string, and you are putting quotes around the value in the insert. So you are effectively trying to insert a string value into a DOUBLE column. Normally MySQL will auto convert strings to doubles, however, my suspicion is that at least some of your getPrice() values are not valid doubles. You can try this instead:
... "', " + Double.parseDouble(stockList.get(i).getPrice()) + ")";
..but if some of the prices are not valid doubles, this will fail as well.
There are some issues with your table and query design:
Use DATE, TIME, or DATETIME types for storing dates and times. LONGBLOB is not meant for this.
The data that is truncated is actually the price you're trying to insert into the DOUBLE column. If getPrice() is returning a string, you need to check decimal and thousant separators. MySQL uses . (point) as decimal and , (comma) as thousant separator by default. And do not use quotes in your query.
When dealing with prices, consider using DECIMAL as type. FLOAT and DOUBLE may not be exact.
I have database with 4 columns int id | String data | String date | int boot and i have some data in it. I have method getRow(String s) when i call it with string for id or data and change query to that option it works but when i´m trying to get row with equal date it won´t pass cursor.moveToFirst condition.
Here is my code:
String CREATE_TABLE = "CREATE TABLE "
+ TABLE_NAME + "(" + COLUMN_ID + " INTEGER PRIMARY KEY AUTOINCREMENT," + COLUMN_DATA
+ " TEXT," + COLUMN_DATE + " TEXT," + COLUMN_BOOT + " Integer" + ")";
public String getRowID(String id){
SQLiteDatabase db = this.getReadableDatabase();
Cursor c = db.rawQuery("select * from " + TABLE_NAME + " where " + COLUMN_ID + " = " + id, null);
if (c != null && c.moveToFirst()) {
//loggin succes
return "string";
}else return null;
}
public String getRowDate(String date){
SQLiteDatabase db = this.getReadableDatabase();
Cursor c = db.rawQuery("select * from " + TABLE_NAME + " where " + COLUMN_DATE + " = " + date, null);
if (c != null && c.moveToFirst()) {
//loggin succes
return "string";
}else return null;
}
myDb.getRowID("1"); returning something
myDb.getRowDate("02122016"); returning null
I have two rows in my database.
1 | 0.19 | 01122016 | 0
2 | 0.19 | 02122016 | 0
Be wary when comparing integers and strings. You may wonder why SQLite would be comparing integers at all since your arguments are strings, until you consider that your raw query looks like this:
select * from TABLE where DATE = 02122016
That value is interpreted as an integer and converted to text, but it loses the leading zero in the process. You can verify this with a sqlite3 shell:
sqlite> select 02122016;
2122016
sqlite> select '02122016' = 02122016;
0 -- false
sqlite> select cast(02122016 as text);
2122016
The simplest fix is to quote the value using a method from DatabaseUtils:
String escaped = DatabaseUtils.sqlEscapeString(date);
String query = "select * from " + TABLE_NAME + " where " + COLUMN_DATE + " = " + escaped;
A better fix would be to use a placeholder argument instead. Note that Android binds all arguments as strings:
String query = "select * from " + TABLE_NAME + " where " + COLUMN_DATE + " = ?";
db.rawQuery(query, new String[]{date});
However, my advice would be to not use rawQuery() and instead use one of the real query() methods. Here's a good example.
Lastly, perhaps you should consider a different format for storing dates. In practice I usually either store an INTEGER column with a unix timestamp (seconds or milliseconds since epoch), or I use a TEXT column with values in the yyyy-MM-dd format since this is implicitly supported by numerous datetime functions in SQLite.
I have a table with four columns, this is how it looks like. I would call it T_BPR_KPI_MONTHLY_VALUES
KPI_NAME_SHORT_S | MONTH_N | YEAR_N | VALUE_N
-----------------------------------------------
MY_KPI_1 | 1 | 2015 | 99.87
MY_KPI_2 | 1 | 2015 | 97.62
... | 1 | 2015 | ...
MY_KPI_1 | 2 | 2015 | ...
... | ... | 2015 | ...
Each kpi represents a measurement and each of them has daily values which are saved in another table called T_BPR_KPI_DY. My goal is to calculate and save monthly values of each KPI.
It is possible that on the certain day, daily values for some kpis are still missing and in order to precisely calculate monthly values I must be able to replace exisisting values in the database as well as insert new etries for the future months and years.
I tought that oracle sql merge operation would be good choice for this task. The idea is to check whether an entry already exists and if so than to update its value and if not to insert new one.
This is how the query looks like
MERGE INTO T_BPR_KPI_MONTHLY_VALUE A
USING( SELECT 'MY_KPI_1' AS KPI_NAME_SHORT_S, 1 AS MONTH_N, 2014 AS YEAR_N FROM DUAL ) B
ON ( A.KPI_NAME_SHORT_S = B.KPI_NAME_SHORT_S )
WHEN MATCHED THEN
UPDATE SET VALUE_N = ( select AVG(MY_KPI_1) from T_BPR_KPI_DY where DAY_D between '01.01.2014' AND '31.01.2014')
WHEN NOT MATCHED THEN
INSERT (KPI_NAME_SHORT_S, MONTH_N, YEAR_N, VALUE_N) VALUES ('MY_KPI_1', 1, 2014, ( select AVG(MY_KPI_1) from T_BPR_KPI_DY where DAY_D between '01.01.2014' AND '31.01.2014') )
I tought that calculating avg monthly values on the fly is not a bad idea, so as you can see I have another select query which only calculates avg monthy value for the specific kpi. I am not sure if this is a best practic solution but it works fine when I execute this query in oracle sql developer tool. however when I try to execute it from the app it does not work.
This is how the method looks like
public static void storeValuesToDb(ArrayList<String> kpiNames) throws SQLException {
Connection conn = getOracleJDBCConnection_DASH();
int currentYear = cal.get(Calendar.YEAR);
int startYear = cal.get(Calendar.YEAR) - 1;
for (String kpiName : kpiNames) {
for (int i = startYear; i <= currentYear; i++) {
for (int j = 0; j < 12; j++) {
try {
String myMergeSQL = ""
+ "MERGE INTO T_BPR_KPI_MONTHLY_VALUE A "
+ "USING( SELECT '" + kpiName + "' AS KPI_NAME_SHORT_S, " + (j + 1) + " AS MONTH_N, " + i + " AS YEAR_N FROM DUAL ) B ON ( A.KPI_NAME_SHORT_S = B.KPI_NAME_SHORT_S ) "
+ "WHEN MATCHED THEN "
+ "UPDATE SET VALUE_N = ( select AVG(" + kpiName + ") from T_BPR_KPI_DY where DAY_D between '" + getFirstDateOfMonth(j, i) + "' AND '" + getLastDateOfMonth(j, i) + "') "
+ "WHEN NOT MATCHED THEN "
+ "INSERT (KPI_NAME_SHORT_S, MONTH_N, YEAR_N, VALUE_N) VALUES ('" + kpiName + "', " + (j + 1) + ", " + i + ", ( select AVG(" + kpiName + ") from T_BPR_KPI_DY where DAY_D between '" + getFirstDateOfMonth(j, i) + "' AND '" + getLastDateOfMonth(j, i) + "') )";
System.out.println(myMergeSQL);
Statement stmt_dash = conn.createStatement();
stmt_dash.executeUpdate(myMergeSQL);
conn.commit();
stmt_dash.close();
} catch (SQLException ex) {
conn.close();
}
}
}
}
conn.close();
}
In terminal it prints out only the first merge sql. It neither finishs the operation nor throws an exception. It blocks somehow and in the db happens also nothing. It could be possible that my merge query is not correct or that it is not possible to execute this kind of operation with statement object. If someone is able to see what cases this issue, please help.
Thx in advance
I would start by reformulating your merge query and solve some issues:
the USING part of a MERGE actually means your "source of raw data". You are using a select from dual with hardcoded values. Here you should select all KPIs and also calculate the Average by KPI. Compose your query that selects all KPIs with their coresponding VALUE_N and use it in the USING part
when matched then UPDATE SET use the values from "source of raw data" which is alias B in your code, not compute on inside the UPDATE clause.
when not matched then INSERT VALUES - again, use values from "source of raw data" which is alias B in your code, do not try to compute the VALUE_N inside the insert - well at least not in that manner I think this is your querys main issue.
MERGE INTO xxx A using () B you gave 2 aliases to your tables but down the line inside the WHEN MATCHED or NOT you are not using the alias. This can raise problems if A and B have similar named columns.
An example of how I use merge in production:
Merge into Destination, using a select from a table Source (inside the select from source you can also add other computations obviously, in your case the average)
T_REPORT_DAILY_SNAPSHOT_2G should be in your code the select kpis name, value and average or whatever you need on INSERT and UPDATE
MERGE INTO T_CELLS_2G dest
USING (SELECT DISTINCT *
FROM T_REPORT_DAILY_SNAPSHOT_2G) src
ON (dest.lac = src.lac and dest.cell_id = src.cell_id)
WHEN MATCHED THEN
UPDATE SET
dest.cell_name = src.cell_name,
dest.loc_code = src.loc_code,
dest.site_code = src.site_code,
dest.rac = src.rac
WHEN NOT MATCHED THEN
INSERT (dest.cell_name,
dest.loc_code,
dest.site_code,
dest.lac,
dest.cell_id,
dest.rac)
VALUES (src.cell_name,
src.loc_code,
src.site_code,
src.lac,
src.cell_id,
src.rac);
Hope this helps in some way.
I'm using the h2 v1.3.176.
I have user-defined function which execute RECURSIVE query.
public static ResultSet getChildCategories(Connection connection, long categoryId) throws SQLException {
String sql =
"WITH RECURSIVE r(CATEGORY_ID, PARENT_ID) AS (\n" +
" SELECT CATEGORY_ID\n" +
" ,PARENT_ID\n" +
" FROM CATEGORY\n" +
" WHERE CATEGORY_ID = " + categoryId + "\n" +
" UNION ALL\n" +
" SELECT CATEGORY.CATEGORY_ID\n" +
" ,CATEGORY.PARENT_ID\n" +
" FROM CATEGORY, r\n" +
" WHERE CATEGORY.PARENT_ID = r.CATEGORY_ID\n" +
")\n" +
"SELECT CATEGORY_ID FROM r";
ResultSet resultSet = connection.createStatement().executeQuery(sql);
SimpleResultSet rs = new SimpleResultSet();
rs.addColumn("CATEGORY_ID", Types.INTEGER, 12, 0);
try {
while(resultSet.next()) {
rs.addRow(resultSet.getLong(1));
}
} finally {
resultSet.close();
}
return rs;
}
I have registered this function by following SQL.
create alias GET_CHILD_CATEGORIES for "com.myapp.db.function.Functions.getChildCategories";
My problem is the getChildCategories function will be called many times when I execute the following query.
SELECT DISTINCT B.BOOK_ID
,B.SERIES_ID
,B.TITLE
,B.ISBN
,B.VOLUME
,(
SELECT MAX(SAME_SERIES.VOLUME)
FROM BOOK SAME_SERIES
WHERE SAME_SERIES.SERIES_ID = B.SERIES_ID
AND SAME_SERIES.VOLUME IS NOT NULL
) AS VOLUME_COUNT
,B.PAGE_COUNT
,B.FILE_PATH
,B.SORTABLE_FILE_NAME
,B.SIZE
,B.HASH
,B.COVER_IMAGE_TYPE
,B.COVER_PAGE_NO
,B.COVER_LARGE_IMAGE_URL
,B.COVER_SMALL_IMAGE_URL
,B.COVER_CROP_COORD
,B.IS_ENCRYPT
,B.PUBLISHER_ID
,B.PUBLISHED_DATE
,B.CREATION_TIME
,B.LAST_MODIFIED_TIME
,B.NOTE
,B.IS_ISBN_SEARCH
,S.CATEGORY_ID
,S.TITLE
,BA.AUTHOR_ID
,BT.TAG_ID
FROM BOOK AS B
INNER JOIN SERIES AS S ON S.SERIES_ID = B.SERIES_ID
LEFT OUTER JOIN BOOK_TAG AS BT ON BT.BOOK_ID = B.BOOK_ID
LEFT OUTER JOIN BOOK_AUTHOR AS BA ON BA.BOOK_ID = B.BOOK_ID
WHERE
(
S.CATEGORY_ID IN (SELECT CATEGORY_ID FROM GET_CHILD_CATEGORIES(106))
And
S.IS_COMPLETION = 1
)
ORDER BY BA.AUTHOR_ID
Why do many times would be called this function?
Extracted from H2 documentation
A function that returns a result set can be used like a table.
However, in this case the function is called at least twice: first
while parsing the statement to collect the column names (with
parameters set to null where not known at compile time). And then,
while executing the statement to get the data (maybe multiple times if
this is a join). If the function is called just to get the column
list, the URL of the connection passed to the function is
jdbc:columnlist:connection. Otherwise, the URL of the connection is
jdbc:default:connection.
The first calls are only to retrieve the resultset column types. Then you have to check if the connection url is "jdbc:columnlist:connection". If true you have to return an empty result set with column list.
The connection url test is:
connection.getMetaData().getURL().equals("jdbc:columnlist:connection");
I am new to Java and MYSql in fact using this combination first time and facing real trouble. I want to insert few records in a table but unable to do so. Following are the fields and datatype in the table named tbl_cdr in MySql.
**Field** **Type**
DATEANDTIME datetime NULL
VALUE1 int(50) NULL
VALUE2 varchar(50) NULL
VALUE3 varchar(50) NULL
VALUE4 varchar(50) NULL
VALUE5 varchar(50) NULL
The record I want to insert contains following values
2014-05-19 02:37:18, 405, MGW190514023718eab4, 923016313475, IN, ALERTSC
I am using following query and statements to Insert record in table
sqlQuery = "INSERT INTO tbl_cdr (DATEANDTIME,VALUE1,VALUE2,VALUE3,VALUE4,VALUE5)" + "VALUES ("+ forDateAndTime.format(date) + ", " + columnsList.get(1) + ", " + columnsList.get(2) + ", " + columnsList.get(3) + ", " + columnsList.get(4) + ", " + columnsList.get(5) + ")";
try
{
Statement qryStatement = conn.createStatement();
qryStatement.executeUpdate(sqlQuery);
qryStatement.close();
} catch (SQLException ex)
{
Logger.getLogger(CdrProject.class.getName()).log(Level.SEVERE, null, ex);
}
But when I reach the statement qryStatement.executeUpdate(sqlQuery); exception is thrown as:
MySQLSyntaxErrorException: You have an error in your SQL syntax;
check the manual that corresponds to your MySQL server version for the
right syntax to use near '02:37:18, 405, MGW190514023718eab4,
923016313475, IN, ALERTSC)' at line 1
value2 ,value3 ,value4 and value 5 are varchars so it should be written within ''.
Do like this
sqlQuery = "INSERT INTO tbl_cdr (DATEANDTIME,VALUE1,VALUE2,VALUE3,VALUE4,VALUE5)" + "VALUES ("+ forDateAndTime.format(date) + ", " + columnsList.get(1) + ", '" + columnsList.get(2) + "',' " + columnsList.get(3) + "',' " + columnsList.get(4) + "',' " + columnsList.get(5) + "')";
You're inserting the date incorrectly. MySQL allows you to insert a string literal or a number.
You're trying to use 02:37:18 as a number, when really you should be using it as a string literal: '02:37:18'
Here is the MySql Reference describing this.
You're also not treating your varchars as strings either, they should be enclosed with quotes.