Parameterized Queries

JustyBase.NetezzaDriver supports both named (:name, @name) and positional (?) parameter placeholders.

How it works

Parameters are rendered inline into the SQL text before execution. The driver parses the SQL, replaces placeholders with properly escaped C#-to-SQL literal representations, and sends the final SQL to the server. There is no binary Bind message — this matches the approach used by the Python nzpy_extended driver.

Named parameters

using var cmd = conn.CreateCommand(
    "SELECT id, name FROM users WHERE age > :minAge AND city = :city");
cmd.Parameters.AddWithValue(":minAge", 18);
cmd.Parameters.AddWithValue(":city", "New York");

using var reader = cmd.ExecuteReader();
while (reader.Read())
    Console.WriteLine($"{reader.GetInt32(0)}: {reader.GetString(1)}");

Both :name and @name prefixes are supported:

cmd.Parameters.AddWithValue(":id", 42);   // colon prefix
cmd.Parameters.AddWithValue("@name", "Alice");  // @ prefix

Positional parameters

Use ? placeholders and mark each parameter with IsPositional = true:

using var cmd = conn.CreateCommand("SELECT * FROM users WHERE status = ? AND age > ?");
cmd.Parameters.Add(new NzParameter { Value = "active", IsPositional = true });
cmd.Parameters.Add(new NzParameter { Value = 18, IsPositional = true });

using var reader = cmd.ExecuteReader();

Important: All positional parameters must have IsPositional = true. Named parameters must have IsPositional = false (default). Mixing named and positional in a single query is not supported.

C# to SQL type mapping

C# type	SQL literal	Example
null / DBNull	NULL	NULL
bool	TRUE / FALSE	TRUE
int, long, short	number literal	42
float, double	number literal	3.14
decimal	number literal	3.14
string	'escaped'	'hello'
DateTime	'yyyy-MM-dd HH:mm:ss.ffffff'	'2024-01-15 10:30:00.000000'
DateOnly	'yyyy-MM-dd'	'2024-01-15'
TimeOnly	'HH:mm:ss'	'14:30:00'
TimeSpan	'HH:mm:ss'	'14:30:00'
byte[]	x'hex'	x'deadbeef'
Guid	'guid'	'xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx'
char	'c' (escaped)	'a'

String values are escaped by doubling single quotes (' → ''). Byte arrays are rendered as hex literals (x'abcd').

Using ADO.NET standard API

using var cmd = conn.CreateCommand("SELECT :val::INTEGER");
var p = cmd.CreateParameter();
p.ParameterName = ":val";
p.Value = 7;
cmd.Parameters.Add(p);
using var reader = cmd.ExecuteReader();

Parameters are not persisted

Each execution rebuilds the SQL with current parameter values. Parameters are cleared after execution, so you must re-add them for each Execute* call.

SQL parsing details

The NzParameterHelper.SubstituteParameters method uses a state-machine parser that:

• Handles string literals ('single quoted')
• Handles identifiers ("quoted", "escaped""quote")
• Handles line comments (--) and block comments (/* */)
• Only replaces :name, @name, and ? outside of literals and comments