protected override void WriteFunctionToSql(QueryExpression queryExpression)
{
switch (queryExpression)
{
case RandomFunctionExpression randomFunctionExpression:
Sql.Append($"FLOOR(RANDOM() * {int.MaxValue})::int");
return;
case LastInsertIdFunctionExpression lastInsertIdExpression:
Sql.Append("LASTVAL()");
return;
case TableExistsVirtualFunctionExpression tableExistsExpression:
ExpressionWriter.Visit(
Postgresql.Raw($@"SELECT 1
FROM pg_catalog.pg_class c
JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
WHERE n.nspname = current_schema()
AND c.relname = '{tableExistsExpression.Table.TableName.Replace("'", "\\'")}'
AND c.relkind = 'r' -- only tables")
);
return;
}
base.WriteFunctionToSql(queryExpression);
}
protected override void WriteFunctionToSql(QueryExpression queryExpression)
{
switch (queryExpression)
{
case ConcatenateQueryExpression concatenateQueryExpression:
for (var i = 0; i < concatenateQueryExpression.Expressions.Length; i++)
{
ExpressionWriter.Visit(concatenateQueryExpression.Expressions[i]);
if (i < concatenateQueryExpression.Expressions.Length - 1)
{
Sql.Append(" || ");
}
}
return;
case LastInsertIdFunctionExpression lastInsertIdExpression:
Sql.Append("last_insert_rowid()");
return;
case TableExistsVirtualFunctionExpression tableExistsExpression:
ExpressionWriter.Visit(
QueryExpression.Select(
new[] { QueryExpression.Value(1) },
from: QueryExpression.Table("sqlite_master"),
where : QueryExpression.AndAlso(
QueryExpression.Compare(QueryExpression.Column("type"), ComparisonOperator.AreEqual, QueryExpression.Value("table")),
QueryExpression.Compare(QueryExpression.Column("name"), ComparisonOperator.AreEqual, QueryExpression.Value(tableExistsExpression.Table.TableName))
)
)
);
return;
}
base.WriteFunctionToSql(queryExpression);
}
