When writing efficient, readable and standardized SQL code, you need to pay attention to the following aspects: 1. Improve code readability and use indentation, line breaks and alias. 2. Optimize query performance, select necessary fields and use indexes. 3. Avoid common mistakes, such as forgetting the WHERE clause or JOIN condition. 4. Combining business requirements and database features, such as using window functions. 5. Use version control tools to manage SQL scripts and refactor the code regularly. Through these methods, we can write more elegant and efficient SQL code.

MySQL itself does not have built-in data sharding function, but can be implemented through architectural design and tools. Data sharding is to split large table data into multiple databases or tables according to rules to improve performance. Common implementation methods include: 1. Hashing fragments by user ID, which are evenly distributed but troublesome to expand capacity; 2. Shaving fragments by range, which are suitable for time-class fields but are easy to hot spots; 3. Consistent hashing algorithms, which reduce the amount of expansion migration but complex implementation. After sharding, cross-slice query, data migration, distributed transactions and other problems need to be dealt with. Middleware such as MyCat, Vitess or application layer logic processing can be used, and shard keys should be selected reasonably, shard balance should be monitored, excessive sharding should be avoided, and backup strategies should be improved.

The top ten exchanges in the currency circle include Binance, Ouyi, Huobi, Gate.io, Kraken, Coinbase, Bitfinex, Bittrex, Poloniex and KuCoin. 1. Binance is known for its high transaction volume and rich trading pairs, but its user interface is complex. 2. Ouyi provides diversified financial products with strong technical support, but the withdrawal speed is slow. 3. Huobi has a long history, but the transaction volume has decreased and the handling fees are high. 4. Gate.io has a wide variety of tokens, low handling fees, but has a small market share.

The top ten exchanges in the currency circle have their own advantages and disadvantages. The choice needs to consider security, liquidity, fees, interface and compliance. 1. Newbie people should choose Coinbase or Bittrex because of its user-friendliness and high security. 2. Professional investors should choose Binance or OKEx because of their high liquidity and diversified trading products.

Directly querying administrator passwords is not recommended in terms of security. The security design principle of Oracle database is to avoid storing passwords in plain text. Alternative methods include: 1. Reset the SYS or SYSTEM user password using SQL*Plus; 2. Verify the encrypted password through the DBMS_CRYPTO package.

The tutorials on using the four major platforms of Binance, Ouyi, Huobi, and gate.io are as follows: 1. Register an account: Visit the official website, click "Register", enter your email and password, and complete verification. 2. Complete KYC verification: Upload your ID and selfies. 3. Deposit: Select the currency, copy the address and send the cryptocurrency. 4. Trading: Select spot trading, enter quantity, and click Buy or Sell. Recommended tools for beginners include TradingView, CoinGecko, Trust Wallet, Ledger Nano S, etc.

Ranking of the top ten digital currency free exchanges in 2025: 1. Binance, 2. OKX, 3. Huobi, 4. Coinbase, 5. Kraken, 6. Bitfinex, 7. KuCoin, 8. Bittrex, 9. Gemini, 10. Poloniex, these exchanges provide free spot trading services, and each has its own advantages, such as an efficient trading system, rich currency support, strong liquidity and user-friendly interface, etc., to ensure the safety of user assets.

For beginners in the currency circle, Binance, Coinbase, CoinGecko, Trust Wallet and Crypto.com are recommended. 1. Binance: a world-leading trading platform, providing a variety of trading models. 2. Coinbase: a user-friendly trading platform that supports fiat currency purchase. 3. CoinGecko: Cryptocurrency data analysis tool that provides market data and news. 4. Trust Wallet: a secure digital wallet that supports multiple cryptocurrencies.