H2 Oracle decode function - h2

In H2, I have written a Java decode function. It works with the code:
String sql = "select decode(1.0,2.0,3.0,4.0) from dual ;";
PreparedStatement stmt = connection.prepareStatement(sql);
ResultSet resultSet = (ResultSet) stmt.executeQuery();
But the code
String sql = "select 6.0 - decode(1.0,2.0,3.0,4.0) from dual ;";
gives the error:
org.h2.jdbc.JdbcSQLException: Hexadecimal string with odd number of characters: "6.0"; SQL statement:
select 6.0 - decode(1.0,2.0,3.0,4.0) from dual ; [90003-157]
at org.h2.message.DbException.getJdbcSQLException(DbException.java:327)
at org.h2.message.DbException.get(DbException.java:167)
at org.h2.message.DbException.get(DbException.java:144)
at org.h2.util.StringUtils.convertHexToBytes(StringUtils.java:943)
at org.h2.value.Value.convertTo(Value.java:826)
at org.h2.expression.Operation.getValue(Operation.java:108)
at org.h2.command.dml.Select.queryFlat(Select.java:518)
at org.h2.command.dml.Select.queryWithoutCache(Select.java:617)
at org.h2.command.dml.Query.query(Query.java:298)
at org.h2.command.dml.Query.query(Query.java:268)
at org.h2.command.dml.Query.query(Query.java:37)
at org.h2.command.CommandContainer.query(CommandContainer.java:80)
at org.h2.command.Command.executeQuery(Command.java:181)
at org.h2.jdbc.JdbcPreparedStatement.executeQuery(JdbcPreparedStatement.java:96)
My decode function is as:
public final static Value decode(Value expression, Value ... paramValues) {
boolean param = true;
boolean hit = false;
Value returnValue = null;
Value defaultValue = null;
// Walk through all parameters, alternately the 'param' and corresponding 'value'.
// If 'param' is equal the expression, then return the next 'value'.
// If no hit, the return the last 'param' value as default value.
for (Value str : paramValues) {
if (param) {
defaultValue = str; // In case this is the last parameter.
// Remember the hit. The next value will be returned.
hit = (MiscUtil.equals(expression, str));
} else {
if (hit) {
returnValue = str;
break; // return str;
}
defaultValue = null;
}
param = ! param;
}
return (returnValue==null) ? defaultValue : returnValue;
}
Is there anything wrong with my decode function?
I have tried to return Object instead of Value in the decode function, and added this code at the end:
Object returnObject=null;
if (returnValue instanceof ValueDecimal) {
returnObject = ((ValueDecimal)returnValue).getBigDecimal();
} else if (returnValue instanceof ValueString) {
returnObject = ((ValueString)returnValue).getString();
} else if (returnValue instanceof ValueDate) {
returnObject = ((ValueDate)returnValue).getDate();
}
return returnValue;
But the I got:
org.h2.jdbc.JdbcSQLException: Data conversion error converting "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"; SQL statement:
select 6.0 - cast(decode(1.0,2.0,3.0,4.0) as double) xxx from dual ; [22018-157]
at org.h2.message.DbException.getJdbcSQLException(DbException.java:327)
at org.h2.message.DbException.get(DbException.java:156)
at org.h2.value.Value.convertTo(Value.java:855)
at org.h2.expression.Function.getSimpleValue(Function.java:733)
at org.h2.expression.Function.getValueWithArgs(Function.java:893)
at org.h2.expression.Function.getValue(Function.java:432)
at org.h2.expression.Operation.getValue(Operation.java:113)
at org.h2.expression.Alias.getValue(Alias.java:35)
...
I also did some try with ValueExpression without luck.
Full support for decode in H2 would be the best solution. Is that something you can provide Thomas?


H2 thinks the data type is JAVA_OBJECT, and therefore wants to convert the parameters (6.0 and the result of the decode) to JAVA_OBJECT, which means first convert to a byte array. This fails.
I didn't test it myself, but explicit CAST should work:
select 6.0 - cast(decode(1.0,2.0,3.0,4.0) as double) from dual
It's a bit ugly I know.

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While looking though some code of the project I'm working on, I've come across a pretty hefty method which does
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Thankfully C# is able to inspect and assign class members dynamically, so one option would be to create a map list and iterate over that.
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You could just loop through all the character from 'A' to 'Z'. It gets difficult because you want to access an attribute of your 'data' object with the corresponding name, but that should (as far as I know) be possible through the C# reflection functionality.
While you get rid of the consecutive if-statements this still won't make your code nice :P

there is a fancy linq solution for your problem using reflection:
but as it was said before: your datastructure is not very well thought through
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var data = new { Z = "test", B="asd"};
Type p = data.GetType();
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in p.GetProperties().OrderBy((fi) => fi.Name)
where fi.Name.Length == 1 && fi.GetValue(data, null) != null
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ta taaaaaaaaa
like that you get the property but the update is not yet done.

var data = _dataRepository.Find(id);
If possible, you should use another DataType without those 26 properties. That new DataType should have 1 property and the Find method should return an instance of that new DataType; then, you could get rid of the 26 if in a more natural way.
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return (char)65; //In this example this si an "A"
And work with some transformation from data.Value to a number between 65 and 90 (A to Z).

Since you always set the lowest alphabet field first and return, you can use an additional field in your class that tracks the first available field. For example, this can be an integer lowest_alphabet_unset and you'd update it whenever you set data.{X}:
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N.B. -- do not use, if data is object rather that structure.
what comes to my mind is that, if A-Z are all same type, then you could theoretically access memory directly to check for non null values.
start = &data;
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return (char) (65 + i);
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}
not tested but to give an idea ;)

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Perhaps you can try this:
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