Drinking half a glass of beer is also a drink driving. For your own life safety, don't take chances and don't drink driving.
 According to the regulations in the Threshold and Inspection of Alcohol Content in Blood and Breath of Vehicle Drivers (GB19522-2004) issued by the State Administration of Quality Supervision, Inspection and Quarantine, the driver who has an alcohol content in blood greater than or equal to 20 mg/100 ml and less than 80 mg/100 ml shall drink and drive; If the alcohol content in the blood is greater than or equal to 80mg/100ml, it is regarded as drunk driving.
 According to expert estimates: 20 mg/100 ml is roughly equivalent to a glass of beer; 80mg/100ml is equivalent to 3 liang low alcohol liquor or two bottles of beer; 100 mg/100 ml is roughly equivalent to half a jin of low alcohol liquor or 3 bottles of beer.
 Legal basis
 Article 91 of the Road Traffic Safety Law of the People's Republic of China, if a person drives a motor vehicle after drinking, his motor vehicle driving license shall be temporarily withheld for six months and he shall be fined not less than 1000 yuan but not more than 2000 yuan. Whoever is punished for driving a motor vehicle after drinking alcohol, and who drives a motor vehicle after drinking again, shall be detained for not more than 10 days, fined not less than 1000 yuan but not more than 2000 yuan, and his motor vehicle driving license shall be revoked. Whoever drives a motor vehicle while intoxicated shall be restrained by the traffic control department of the public security organ until he wakes up, his motor vehicle driving license shall be revoked, and criminal responsibility shall be investigated according to law; No motor vehicle driver's license may be obtained again within five years. Whoever drives a motor vehicle after drinking alcohol shall be detained for 15 days and fined 5000 yuan, his motor vehicle driving license shall be revoked, and he shall not obtain a new motor vehicle driving license within five years.
 If a person drives a motor vehicle while drunk, the traffic control department of the public security organ shall restrain him until he wakes up, revoke his motor vehicle driving license, and investigate his criminal responsibility according to law; It is not allowed to obtain a new motor vehicle driving license within ten years. After obtaining a new motor vehicle driving license, it is not allowed to drive a commercial motor vehicle. If a serious traffic accident occurs after drinking or driving a motor vehicle while intoxicated, which constitutes a crime, criminal responsibility shall be investigated according to law, and the traffic control department of the public security organ shall revoke the motor vehicle driver's license, and may not obtain a new motor vehicle driver's license for life.