MySQL to Postgres conversion - mysql

Question

Does anyone know what could be causing this error? I'm trying to convert a MySQL site to Postgres so I can host on Heroku. I'm new to database syntax, and this problem has been bugging me for days.
PG::Error: ERROR: syntax error at or near "ON"
LINE 1: ...tores ("key", "value") VALUES ('traffic:hits', 0) ON DUPLICA...
^
Here's the github page for the site I'm trying to convert. https://github.com/jcs/lobsters
This is the query. I added the backslash double quotes in replace of `.
if Rails.env == "test"
Keystore.connection.execute("INSERT OR IGNORE INTO " <<
"#{Keystore.table_name} (\"key\", \"value\") VALUES " <<
"(#{q(key)}, 0)")
Keystore.connection.execute("UPDATE #{Keystore.table_name} " <<
"SET \"value\" = \"value\" + #{q(amount)} WHERE \"key\" = #{q(key)}")
else
Keystore.connection.execute("INSERT INTO #{Keystore.table_name} (" +
"\"key\", \"value\") VALUES (#{q(key)}, #{q(amount)}) ON DUPLICATE KEY " +
"UPDATE \"value\" = \"value\" + #{q(amount)}")
end

Answer 1

Postgres' INSERT doesn't support MySQL's variant INSERT ... ON DUPLICATE KEY UPDATE.
For alternatives see the answers to this question.

Answer 2

I was working on this exact code last night, here's an initial take at how I fixed it, following this answer :
def self.put(key, value)
key_column = Keystore.connection.quote_column_name("key")
value_column = Keystore.connection.quote_column_name("value")
if Keystore.connection.adapter_name == "SQLite"
Keystore.connection.execute("INSERT OR REPLACE INTO " <<
"#{Keystore.table_name} (#{key_column}, #{value_column}) VALUES " <<
"(#{q(key)}, #{q(value)})")
elsif Keystore.connection.adapter_name == "PostgreSQL"
Keystore.connection.execute("UPDATE #{Keystore.table_name} " +
"SET #{value_column} =#{q(value)} WHERE #{key_column} =#{q(key)}")
Keystore.connection.execute("INSERT INTO #{Keystore.table_name} (#{key_column}, #{value_column}) " +
"SELECT #{q(key)}, #{q(value)} " +
"WHERE NOT EXISTS (SELECT 1 FROM #{Keystore.table_name} WHERE #{key_column} = #{q(key)}) "
)
elsif Keystore.connection.adapter_name == "MySQL" || Keystore.connection.adapter_name == "Mysql2"
Keystore.connection.execute("INSERT INTO #{Keystore.table_name} (" +
"#{key_column}, #{value_column}) VALUES (#{q(key)}, #{q(value)}) ON DUPLICATE KEY " +
"UPDATE #{value_column} = #{q(value)}")
else
raise "Error: keystore requires db-specific put method."
end
true
end
There's a number of things to be fixed in the lobsters codebase beyond just this for postgres compatability - found mysql specific things in other controller files. I'm currently working on them at my own lobsters fork at https://github.com/seltzered/journaltalk - postgres fixes should be commited on there in the coming day or two.